#include <iostream>
#include <cstdio>
using namespace std;
 
int main() {
	int adj[105][105]={0}, b[105]={0}, g[105]={0}, f, cnt, flag=0, n;
	scanf("%d", &n);
	for(int i=0; i<n; i++) {
		cnt=0;
		while(true) {
			scanf("%d", &f);
			if(f==0 && cnt==0) {flag=1; break;}
			else if(f==0) break;
			adj[i][f-1]=1, cnt++;
		}
	}
	cnt=0;
	for(int i=0; i<n; i++) {
		for(int j=0; j<n; j++) {
			if(adj[i][j]==1 && b[j]==0) {
				b[i]=b[j]=1;
				if(g[i]==1) g[j]=2;
				else g[j]=1, cnt++;
			}
		}
	}
	if(flag==1) printf("0");
	else {
		printf("%d\n", cnt);
		for(int i=0; i<n; i++) if(g[i]==1) printf("%d ", i+1);
	}
	return 0;
}

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NwoyIDMgMAozIDEgMAoxIDIgNCA1IDAKMyAwCjMgMAo3IDAKNiAw

7
2 3 0
3 1 0
1 2 4 5 0
3 0
3 0
7 0
6 0