# your code goes here
class Solution:
def smallestSubstring(self, s:str) -> str:
result = ''
i,j = 0,0
for i in range(len(s)):
result += s[i]
temp = ''
for j in range(len(s)):
if (len(temp) == len(s)):
break
temp += result
if (temp == s):
break
return result
if __name__ == '__main__':
s = Solution()
inp = input()
print(s.smallestSubstring(inp))
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