Compilare: main.cpp: In function 'int main()': main.cpp:66:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 1; i < ans.size(); i++) { ~~^~~~~~~~~~~~ main.cpp:46:32: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("cool.in", "r", stdin); ^ main.cpp:47:34: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("cool.out", "w", stdout); ^