Compilare: user.cpp: In function ‘int main()’: user.cpp:59:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<b.size();++i) { ^ user.cpp:63:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<b.size();++i) { ^ user.cpp:32:29: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("nop.in","r",stdin); ^ user.cpp:33:31: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("nop.out","w",stdout); ^ user.cpp:47:16: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&T); ^ user.cpp:49:23: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&N); ^