Compilare: user.cpp: In function ‘int main()’: user.cpp:37:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1;i<=n;i++) ^ user.cpp:44:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1;i<=n;i++){ ^ user.cpp:33:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("copaci.in","r",stdin); ^ user.cpp:34:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("copaci.out","w",stdout); ^ user.cpp:36:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&n); ^ user.cpp:38:43: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%ld %ld",&a[i].x,&a[i].y); ^