Compilare: user.cpp: In function ‘int main()’: user.cpp:66:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < ec.size(); i++) { ^ user.cpp:68:41: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(i > 0 && i < ec.size() - 1) { ^ 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("tester.in", "r", stdin); ^ user.cpp:35:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("tester.out", "w", stdout); ^ user.cpp:37:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &n, &m); ^ user.cpp:39:50: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &e[i].first, &e[i].second); ^