Compilare: user.cpp: In function ‘int main()’: user.cpp:52:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < v.size(); ++i) ^ user.cpp:53:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (i != v.size() - 1)arie = arie +abs(x * v[i].second + v[i].first * v[i + 1].second + v[i + 1].first * y - (v[i].first * y + v[i].second * v[i + 1].first + v[i + 1].second * x)) / 2; ^ user.cpp:15:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("zona.in","r",stdin); ^ user.cpp:16:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("zona.out","w",stdout); ^ user.cpp:19:43: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d %d\n", &x, &y, &n, &q); ^ user.cpp:30:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &d); ^