Compilare: user.cpp: In function ‘int main()’: user.cpp:50:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 1; i < v.size(); ++ i) { ^ user.cpp:51:60: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if( fabs(v[i] - v[i - 1]) < eps && i != v.size() - 1 ) { ^ user.cpp:19:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("trapez.in", "r", stdin); ^ user.cpp:20:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("trapez.out", "w", stdout); ^ user.cpp:23:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^ user.cpp:27:30: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &x, &y); ^