#include <bits/stdc++.h>
#define endl '\n'
using namespace std;
 
int n;
int d[]={1,10,11,100,101,110,111,1000,1001,1010,1011,1100,1101,1110,1111,10000,10001,10010,10011,10100,10101,10110,10111,11000,11001,11010,11011,11100,11101,11110,11111,100000,100001,100010,100011,100100,100101,100110,100111,101000,101001,101010,101011,101100,101101,101110,101111,110000,110001,110010,110011,110100,110101,110110,110111,111000,111001,111010,111011,111100,111101,111110,111111,1000000,1000001,1000010,1000011,1000100,1000101,1000110,1000111,1001000,1001001,1001010,1001011,1001100,1001101,1001110,1001111,1010000,1010001,1010010,1010011,1010100,1010101,1010110,1010111,1011000,1011001,1011010,1011011,1011100,1011101,1011110,1011111,1100000,1100001,1100010,1100011,1100100,1100101,1100110,1100111,1101000,1101001,1101010,1101011,1101100,1101101,1101110,1101111,1110000,1110001,1110010,1110011,1110100,1110101,1110110,1110111,1111000,1111001,1111010,1111011,1111100,1111101,1111110,1111111,10000000,10000001,10000010,10000011,10000100,10000101,10000110,10000111,10001000,10001001,10001010,10001011,10001100,10001101,10001110,10001111,10010000,10010001,10010010,10010011,10010100,10010101,10010110,10010111,10011000,10011001,10011010,10011011,10011100,10011101,10011110,10011111,10100000,10100001,10100010,10100011,10100100,10100101,10100110,10100111,10101000,10101001,10101010,10101011,10101100,10101101,10101110,10101111,10110000,10110001,10110010,10110011,10110100,10110101,10110110,10110111,10111000,10111001,10111010,10111011,10111100,10111101,10111110,10111111,11000000,11000001,11000010,11000011,11000100,11000101,11000110,11000111,11001000,11001001,11001010,11001011,11001100,11001101,11001110,11001111,11010000,11010001,11010010,11010011,11010100,11010101,11010110,11010111,11011000,11011001,11011010,11011011,11011100,11011101,11011110,11011111,11100000,11100001,11100010,11100011,11100100,11100101,11100110,11100111,11101000,11101001,11101010,11101011,11101100,11101101,11101110,11101111,11110000,11110001,11110010,11110011,11110100,11110101,11110110,11110111,11111000,11111001,11111010,11111011,11111100,11111101,11111110,11111111,100000000,100000001,100000010,100000011,100000100,100000101,100000110,100000111,100001000,100001001,100001010,100001011,100001100,100001101,100001110,100001111,100010000,100010001,100010010,100010011,100010100,100010101,100010110,100010111,100011000,100011001,100011010,100011011,100011100,100011101,100011110,100011111,100100000,100100001,100100010,100100011,100100100,100100101,100100110,100100111,100101000,100101001,100101010,100101011,100101100,100101101,100101110,100101111,100110000,100110001,100110010,100110011,100110100,100110101,100110110,100110111,100111000,100111001,100111010,100111011,100111100,100111101,100111110,100111111,101000000,101000001,101000010,101000011,101000100,101000101,101000110,101000111,101001000,101001001,101001010,101001011,101001100,101001101,101001110,101001111,101010000,101010001,101010010,101010011,101010100,101010101,101010110,101010111,101011000,101011001,101011010,101011011,101011100,101011101,101011110,101011111,101100000,101100001,101100010,101100011,101100100,101100101,101100110,101100111,101101000,101101001,101101010,101101011,101101100,101101101,101101110,101101111,101110000,101110001,101110010,101110011,101110100,101110101,101110110,101110111,101111000,101111001,101111010,101111011,101111100,101111101,101111110,101111111,110000000,110000001,110000010,110000011,110000100,110000101,110000110,110000111,110001000,110001001,110001010,110001011,110001100,110001101,110001110,110001111,110010000,110010001,110010010,110010011,110010100,110010101,110010110,110010111,110011000,110011001,110011010,110011011,110011100,110011101,110011110,110011111,110100000,110100001,110100010,110100011,110100100,110100101,110100110,110100111,110101000,110101001,110101010,110101011,110101100,110101101,110101110,110101111,110110000,110110001,110110010,110110011,110110100,110110101,110110110,110110111,110111000,110111001,110111010,110111011,110111100,110111101,110111110,110111111,111000000,111000001,111000010,111000011,111000100,111000101,111000110,111000111,111001000,111001001,111001010,111001011,111001100,111001101,111001110,111001111,111010000,111010001,111010010,111010011,111010100,111010101,111010110,111010111,111011000,111011001,111011010,111011011,111011100,111011101,111011110,111011111,111100000,111100001,111100010,111100011,111100100,111100101,111100110,111100111,111101000,111101001,111101010,111101011,111101100,111101101,111101110,111101111,111110000,111110001,111110010,111110011,111110100,111110101,111110110,111110111,111111000,111111001,111111010,111111011,111111100,111111101,111111110,111111111,1000000000};
int sol=0;
 
void start(){
	cin>>n;
	for(int i=0;i<512;i++){
		if(d[i]>n){
			cout<<sol<<endl;
			return;
		}
		else sol++;
	}
	cout<<sol<<endl;
 
}
 
int main(){
	ios_base::sync_with_stdio(false); cin.tie(NULL);
	start();
	return 0;
}

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MTAxMDAwMTAsMTEwMTAwMDExLDExMDEwMDEwMCwxMTAxMDAxMDEsMTEwMTAwMTEwLDExMDEwMDExMSwxMTAxMDEwMDAsMTEwMTAxMDAxLDExMDEwMTAxMCwxMTAxMDEwMTEsMTEwMTAxMTAwLDExMDEwMTEwMSwxMTAxMDExMTAsMTEwMTAxMTExLDExMDExMDAwMCwxMTAxMTAwMDEsMTEwMTEwMDEwLDExMDExMDAxMSwxMTAxMTAxMDAsMTEwMTEwMTAxLDExMDExMDExMCwxMTAxMTAxMTEsMTEwMTExMDAwLDExMDExMTAwMSwxMTAxMTEwMTAsMTEwMTExMDExLDExMDExMTEwMCwxMTAxMTExMDEsMTEwMTExMTEwLDExMDExMTExMSwxMTEwMDAwMDAsMTExMDAwMDAxLDExMTAwMDAxMCwxMTEwMDAwMTEsMTExMDAwMTAwLDExMTAwMDEwMSwxMTEwMDAxMTAsMTExMDAwMTExLDExMTAwMTAwMCwxMTEwMDEwMDEsMTExMDAxMDEwLDExMTAwMTAxMSwxMTEwMDExMDAsMTExMDAxMTAxLDExMTAwMTExMCwxMTEwMDExMTEsMTExMDEwMDAwLDExMTAxMDAwMSwxMTEwMTAwMTAsMTExMDEwMDExLDExMTAxMDEwMCwxMTEwMTAxMDEsMTExMDEwMTEwLDExMTAxMDExMSwxMTEwMTEwMDAsMTExMDExMDAxLDExMTAxMTAxMCwxMTEwMTEwMTEsMTExMDExMTAwLDExMTAxMTEwMSwxMTEwMTExMTAsMTExMDExMTExLDExMTEwMDAwMCwxMTExMDAwMDEsMTExMTAwMDEwLDExMTEwMDAxMSwxMTExMDAxMDAsMTExMTAwMTAxLDExMTEwMDExMCwxMTExMDAxMTEsMTExMTAxMDAwLDExMTEwMTAwMSwxMTExMDEwMTAsMTExMTAxMDExLDExMTEwMTEwMCwxMTExMDExMDEsMTExMTAxMTEwLDExMTEwMTExMSwxMTExMTAwMDAsMTExMTEwMDAxLDExMTExMDAxMCwxMTExMTAwMTEsMTExMTEwMTAwLDExMTExMDEwMSwxMTExMTAxMTAsMTExMTEwMTExLDExMTExMTAwMCwxMTExMTEwMDEsMTExMTExMDEwLDExMTExMTAxMSwxMTExMTExMDAsMTExMTExMTAxLDExMTExMTExMCwxMTExMTExMTEsMTAwMDAwMDAwMH07CmludCBzb2w9MDsKCnZvaWQgc3RhcnQoKXsKCWNpbj4+bjsKCWZvcihpbnQgaT0wO2k8NTEyO2krKyl7CgkJaWYoZFtpXT5uKXsKCQkJY291dDw8c29sPDxlbmRsOwoJCQlyZXR1cm47CgkJfQoJCWVsc2Ugc29sKys7Cgl9Cgljb3V0PDxzb2w8PGVuZGw7CgkKfQoKaW50IG1haW4oKXsKCWlvc19iYXNlOjpzeW5jX3dpdGhfc3RkaW8oZmFsc2UpOyBjaW4udGllKE5VTEwpOwoJc3RhcnQoKTsKCXJldHVybiAwOwp9

MTAxMDExMCAxMDAwMDAgMTExMDAwMCAxMDEwMTEwMDEgMTEwMTAwMSAxMTAxMTAwIDExMDExMTEgMTAxMTExMTEwIDExMDAxMDEgMTEwMTExMCAxMTEwMTAwMSAxMDAwMDAgMTExMDEwMCAxMTAwMDAxIDExMDAwMTAgMTExMDEwMSAxMTAxMTAwIDExMDAwMTEgMTEwMDEwMSAxMDAwMDAgMTExMDExMCAxMTExMDAxIDExMTAxMDAgMTExMDExMCAxMTAxMTExIDEwMTAxMTAwMSAxMDAwMDAgMTExMDExMCAxMDAwMDAgMTEwMTEwMSAxMTAxMTExIDExMDAxMDAgMTExMDAxMCAxMTEwMTAwMSAxMTAxMTAxIDEwMDAwMCAxMTEwMDAwIDExMDExMTEgMTEwMTEwMCAxMTAxMDAxIDEwMDAwMCAxMTEwMTEwIDExMTEwMTAgMTEwMTExMSAxMTEwMDEwIDExMDAwMTEgMTEwMDEwMSAxMDExMDAgMTAwMDAwIDExMDEwMTEgMTExMDEwMCAxMTAwMTAxIDExMTAwMTAgMTExMDEwMDEgMTAwMDAwIDExMDAwMTAgMTExMDEwMSAxMTAwMTAwIDExMDExMTEgMTExMDEwMSAxMDAwMDAgMTExMDAwMCAxMTAxMTExIDEwMDAwMTEwMSAxMTEwMTEwMSAxMTEwMTAwIDExMDAwMDEgMTExMDEwMCAxMDAwMDAgMTExMDEwMCAxMTEwMTEwIDEwMTEwMTExMSAxMTAxMDEwIDEwMDAwMCAxMDAwMDExMDEgMTEwMDAwMSAxMTEwMDExIDEwMDAwMCAxMTEwMDExIDExMTAxMDAgMTExMDAxMCAxMTEwMDAwMSAxMTEwMTEwIDExMDAxMDEgMTEwMTExMCAxMTExMTEwMSAxMDAwMDAgMTExMDExMCAxMTAwMTAxIDEwMDAwMCAxMDExMDAwMDEgMTEwMTAxMSAxMTAxMTExIDExMDExMDAgMTEwMDEwMSAxMDExMTA=

1010110 100000 1110000 101011001 1101001 1101100 1101111 101111110 1100101 1101110 11101001 100000 1110100 1100001 1100010 1110101 1101100 1100011 1100101 100000 1110110 1111001 1110100 1110110 1101111 101011001 100000 1110110 100000 1101101 1101111 1100100 1110010 11101001 1101101 100000 1110000 1101111 1101100 1101001 100000 1110110 1111010 1101111 1110010 1100011 1100101 101100 100000 1101011 1110100 1100101 1110010 11101001 100000 1100010 1110101 1100100 1101111 1110101 100000 1110000 1101111 100001101 11101101 1110100 1100001 1110100 100000 1110100 1110110 101101111 1101010 100000 100001101 1100001 1110011 100000 1110011 1110100 1110010 11100001 1110110 1100101 1101110 11111101 100000 1110110 1100101 100000 101100001 1101011 1101111 1101100 1100101 101110