Compilare: user.cpp: In function ‘long long int area(std::vector<int>)’: user.cpp:54:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1;i<v.size()-1;i++) ^ user.cpp: In function ‘void convex_hull(std::vector<int>&, std::vector<int>&)’: user.cpp:67:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=2;i<v.size();i++) ^ user.cpp: In function ‘std::string make_string(std::vector<int>, std::vector<int>)’: user.cpp:94:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0;j<v.size();j++) ^ user.cpp:99:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0;j<i.size();j++) ^ user.cpp: In function ‘int main()’: user.cpp:111:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("gradina.in", "r", stdin); ^ user.cpp:113:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^ user.cpp:116:43: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &a[i].first, &a[i].second); ^