Compilare: user.cpp: In function ‘void convex_hull(std::vector<int>&)’: user.cpp:39:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1;i<v1.size();i++) ^ user.cpp:44:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<v1.size();i++) ^ user.cpp: In function ‘void inc(int&)’: user.cpp:98:33: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(pars,1,buff,stdin); ^ user.cpp: In function ‘int main()’: user.cpp:113:35: 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:114:37: 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); ^