Compilare: user.cpp: In function ‘void convex_hull(std::vector<punct>&)’: user.cpp:34:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1;i<v.size();i++) ^ user.cpp:41:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<v.size();i++) ^ user.cpp: In function ‘int main()’: user.cpp:89:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("tri3.in", "r", stdin); ^ user.cpp:90:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("tri3.out", "w", stdout); ^ user.cpp:92:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&n,&m); ^ user.cpp:93:56: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] for(int i=1;i<=n;i++) scanf("%d%d",&v[i].x,&v[i].y); ^ user.cpp:101:46: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d%d",&a.x,&a.y,&b.x,&b.y); ^