Compilare: user.cpp: In function ‘int main()’: user.cpp:85:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<downpoints.size();upp++) ^ user.cpp:88:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(i<downpoints.size() && !comp(uppoints[upp],uppoints[upp+1],downpoints[i])) i++; ^ user.cpp:64:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("oypara.in","r",stdin); ^ user.cpp:65:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("oypara.out","w",stdout); ^ user.cpp:66:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&n); ^ user.cpp:69:35: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d",&x,&ya,&yb); ^