Compilare: user.cpp: In function ‘int main()’: user.cpp:49:36: warning: operation on ‘k’ may be undefined [-Wsequence-point] st[++k] = G[st[k-1]][0]; ^ user.cpp:55:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0; i<ans.size() - 1; i++) ^ user.cpp:23:42: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("ciclueuler.in", "r", stdin); ^ user.cpp:24:44: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("ciclueuler.out", "w", stdout); ^ user.cpp:26:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d %d", &n, &m); ^ user.cpp:29:32: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d %d", &x, &y); ^