Compilare: user.cpp: In function ‘void dfs(int)’: user.cpp:18:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < gr[x].size(); i++) ^ user.cpp: In function ‘int main()’: user.cpp:25:6: warning: unused variable ‘s’ [-Wunused-variable] int s, x, y; ^ user.cpp:27:29: 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:28:31: 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:30:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &n, &m); ^ user.cpp:32:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &x, &y); ^