Compilare: user.cpp: In function ‘void dfs(int)’: user.cpp:10:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int k=0; k<L[x].size(); k++) ^ user.cpp: In function ‘int main()’: user.cpp:16:31: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] {freopen("dfs.in", "r", stdin); ^ user.cpp:17:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("dfs.out", "w", stdout); ^ user.cpp:18:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &n, &m); ^ user.cpp:21:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &x, &y); ^