Compilare: user.cpp: In function ‘int main()’: user.cpp:50:36: warning: operation on ‘k’ may be undefined [-Wsequence-point] st[++k] = G[st[k-1]][0]; ^ user.cpp:24:42: 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:25:44: 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:27:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d %d", &n, &m); ^ user.cpp:30:32: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d %d", &x, &y); ^