Compilare: user.cpp: In function ‘int main()’: user.cpp:47:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<pct.size();++i) ^ user.cpp:48:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=i+1;j<pct.size();++j) ^ user.cpp:53:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 1;i < v.size();i++) ^ user.cpp:34:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("trapez.in","r",stdin); ^ user.cpp:35:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("trapez.out","w",stdout); ^ user.cpp:39:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&n); ^ user.cpp:42:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d",&x,&y); ^