Compilare: user.cpp: In function ‘void DFS2(int, int)’: user.cpp:39:44: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 0; i < G[nod].size(); ++i) ^ user.cpp:44:42: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 0; i < G[1].size()&&ok; ++i) ^ user.cpp:49:44: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 0; i < G[nod].size(); ++i) ^ user.cpp:53:42: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 0; i < G[1].size()&&ok; ++i) ^ user.cpp:58:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 0; i < G[nod].size(); ++i) ^ user.cpp:62:42: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 0; i < G[1].size()&&ok; ++i) ^ user.cpp: In function ‘int main()’: user.cpp:73:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("arbxyz.in","r",stdin); ^ user.cpp:74:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("arbxyz.out","w",stdout); ^ user.cpp:76:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d\n",&t); ^ user.cpp:79:43: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d %d\n",&N,&x,&y,&z); ^ user.cpp:87:36: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d\n",&a,&aa); ^