Compilare: main.cpp: In function 'void dfs(int)': main.cpp:13:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0 ; i < v[nod].size() ; i ++) ~~^~~~~~~~~~~~~~~ main.cpp: In function 'void dfs2(int, int)': main.cpp:23:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0 ; i < pred[nod].size() ; i ++) ~~^~~~~~~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:58:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0 ; j < mat[i].size() ; j ++) ~~^~~~~~~~~~~~~~~ main.cpp:34:36: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("ctc.in" , "r" , stdin); ^ main.cpp:35:38: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("ctc.out" , "w" , stdout); ^ main.cpp:36:28: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d" , &n , &m); ^ main.cpp:39:31: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d" , &x, &y); ^