Compilare: user.cpp: In function ‘int main()’: user.cpp:49:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<id[0].size();i++) ans[ id[0][i] ] = '+'; ^ user.cpp:50:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<id[1].size();i++) ans[ id[1][i] ] = '-'; ^ user.cpp:20:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("semne.in","r",stdin); ^ user.cpp:21:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("semne.out","w",stdout); ^ user.cpp:23:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%ld %lld",&n,&s); ^ user.cpp:26:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%lld",&v[i]); ^