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:54:42: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 0; i < G[1].size()&&ok; ++i) ^ user.cpp:59:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 0; i < G[nod].size(); ++i) ^ user.cpp:63:42: 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:74:36: 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:75:38: 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:77:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d\n",&t); ^ user.cpp:80:43: 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:88:36: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d\n",&a,&aa); ^