Compilare: user.cpp: In function ‘bool dfs(int)’: user.cpp:18:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < v[x].size(); j++) ^ user.cpp:26:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < v[x].size(); j++) ^ user.cpp: In function ‘int main()’: user.cpp:38:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("java.in", "r", stdin); ^ user.cpp:39:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("java.out", "w", stdout); ^ user.cpp:41:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &T); ^ user.cpp:50:38: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d", &n, &m, &e); ^ user.cpp:52:54: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &x, &y), v[x].push_back(y); ^