Compilare: main.cpp: In function 'int main()': main.cpp:31:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<ans.size();i++) ~^~~~~~~~~~~ main.cpp: In function 'void fast()': main.cpp:12:37: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("armonica.in","r",stdin); ^ main.cpp:13:39: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("armonica.out","w",stdout); ^