>           scanf("%d",&N);
>           S=0;
>           for (int i=0;i<N;i++){
>               scanf("%d",&x);
>               S^=(x<<i);
>           }
>           for (int i=0;i<N;i++){
>               scanf("%d",&x);
>               S^=(x<<i);
>           }
>           for (int i=0;i<N;i++)A[i]=((S&(1<<i))&&1)+(1<<(i+1));
>           while (scanf("%d %d",&x,&y),x+y)A[y-1]|=(1<<x);
>           res=N;
>           for (int i=0;i<N;i++){
>               k=i;
>               for (int j=i+1;j<N;j++)if (A[j]>A[k])k=j;
>               x=A[i];A[i]=A[k];A[k]=x;
>               if (A[i]<2){
>                  res=i;
>                  break;
>               }
>               for (int j=i+1;j<N;j++)if (HighestBit(A[i])==HighestBit(A[j]))A[j]^=A[i];
>           }
>           if (res<N && A[res])puts("Oh,it's impossible~!!");
>           else printf("%d\n",1<<(N-res));

嗯，对