Compilare: user.cpp: In function ‘int main()’: user.cpp:55:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < s.size(); i += k) ^ user.cpp:58:43: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = i; j < i + k && j < s.size(); j++) ^ user.cpp:45:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("smooth2.in", "r", stdin); ^ user.cpp:46:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("smooth2.out", "w", stdout); ^