Compilare: user.cpp: In function ‘void Dfs(int)’: user.cpp:78:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 0; i < v[x].size(); ++ i) ^ user.cpp: In function ‘void read()’: user.cpp:18:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("import.in", "r", stdin); ^ user.cpp:19:34: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d", &n, &m, &k); ^ user.cpp:26:31: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &x, &y); ^ user.cpp:35:45: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d %d", &a, &b, &c, &d); ^ user.cpp: In function ‘void write()’: user.cpp:89:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("import.out", "w", stdout); ^