Compilare: user.cpp: In function ‘void erase_edge(int, int)’: user.cpp:30:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < G[u].size(); ++ i) ^ user.cpp: In function ‘int main()’: user.cpp:48:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &N, &M); ^ user.cpp:51:31: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &x, &y); ^