Compilare: main.cpp: In function 'int main()': main.cpp:67:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<ans.size();i++){ ~^~~~~~~~~~~ main.cpp:43:32: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("apm.in","r",stdin); ^ main.cpp:44:34: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("apm.out","w",stdout); ^