Compilare: user.cpp: In function ‘int main()’: user.cpp:78:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int l=0;l<sub.size();l++){ ^ user.cpp:33:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("ndap.in","r",stdin); ^ user.cpp:34:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("ndap.out","w",stdout); ^ user.cpp:37:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d%d",&n,&m); ^ user.cpp:41:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d%d",&a,&b); ^