Compilare: user.cpp: In function ‘int main()’: user.cpp:44:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<s.size();i++) ^ user.cpp:45:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=i+1;j<s.size();j++){ ^ user.cpp:31:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("cmap.in","r",stdin); ^ user.cpp:32:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("cmap.out","w",stdout); ^ user.cpp:33:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&n); ^ user.cpp:35:38: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&v[i].x,&v[i].y); ^