Compilare: main.cpp: In function 'int main()': main.cpp:78:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<fr.size(); i++) ~^~~~~~~~~~ main.cpp:40:37: 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); ^ main.cpp:41:39: 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); ^ main.cpp:43:20: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^ main.cpp:47:50: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &p[i].first, &p[i].second); ^