Compilare: user.cpp: In function ‘void dfs(int)’: user.cpp:15:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0; j < n.size(); j++){ ^ user.cpp: In function ‘int main()’: user.cpp:33:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("sortaret.in","r",stdin); ^ user.cpp:34:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("sortaret.out","w",stdout); ^ user.cpp:35:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&n,&m); ^ user.cpp:38:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&x,&y); ^