Compilare: user.cpp: In function ‘int main()’: user.cpp:30:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(k = 0; k < G[j].size(); k++) ^ user.cpp:22:9: warning: variable ‘i2’ set but not used [-Wunused-but-set-variable] int i2, j, k; ^ user.cpp:13:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("sortaret.in", "rt", stdin); ^ user.cpp:14:42: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("sortaret.out", "wt", stdout); ^ user.cpp:18:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d\n", &N, &M); ^ user.cpp:20:53: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &a, &b), G[a].pb(b), deg[b]++; ^