#include <bits/stdc++.h>
using namespace std;
 
int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
 
    // dp[i][j][t]: số tập hợp chọn từ 1..i có j phần tử và tổng = t
    int dp[21][11][156] = {0};
    dp[0][0][0] = 1;
 
    for (int i = 1; i <= 20; ++i) {
        for (int j = 0; j <= 10; ++j) {
            for (int t = 0; t <= 155; ++t) {
                dp[i][j][t] = dp[i-1][j][t];
                if (j > 0 && t >= i)
                    dp[i][j][t] += dp[i-1][j-1][t - i];
            }
        }
    }
 
    while (true) {
        int n, k, s;
        cin >> n >> k >> s;
        if (n == 0 && k == 0 && s == 0) break;
        cout << dp[n][k][s] << "\n";
    }
 
    return 0;
}

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