Compilare: user.cpp: In function ‘int main()’: user.cpp:44:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 0; i < a.size(); i++) ^ user.cpp:29:41: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("heavymetal.in", "r", stdin); ^ user.cpp:30:43: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("heavymetal.out", "w", stdout); ^ user.cpp:32:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^ user.cpp:35:42: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &v[i].st, &v[i].dr); ^