#include<iostream>
#include<cstdio>
#include<cstring>
#include<string>
#include<map>
#include<vector>
#include<stack>
#include<set>
#include<map>
#include<queue>
#include<algorithm>
#include<cmath>
#define LL long long
//#pragma comment(linker, "/STACK:1024000000,1024000000")
using namespace std;const int N=2005;
const int INF=0x3f3f3f3f;
//typedef pair<int,int>point;
int head[N],I;
struct node
{int j,next;
}side[N*2000];
int dfn[N],low[N],f[N],deep;
bool visited[N],in[N];
int sum[N];
stack<int>st;
void add(int i,int j)
{side[I].j=j;side[I].next=head[i];head[i]=I++;
}
void dfs(int x)
{dfn[x]=low[x]=deep++;st.push(x);in[x]=true;visited[x]=true;for(int t=head[x];t!=-1;t=side[t].next){int j=side[t].j;if(!visited[j]){dfs(j);low[x]=min(low[x],low[j]);}else if(in[j]){low[x]=min(low[x],dfn[j]);}}if(low[x]==dfn[x]){while(st.top()!=x){in[st.top()]=false;f[st.top()]=x;st.pop();}in[st.top()]=false;f[st.top()]=x;st.pop();}
}
int main()
{int n;while(scanf("%d",&n)!=EOF){memset(head,-1,sizeof(head));I=0;for(int i=1;i<=n;++i){int k;while(scanf("%d",&k)){if(k==0) break;add(i,k);}}while(!st.empty())st.pop();memset(in,false,sizeof(in));memset(visited ,false,sizeof(visited));deep=1;for(int i=1;i<=n;++i)if(!visited[i])dfs(i);memset(sum,0,sizeof(sum));for(int i=1;i<=n;++i){for(int t=head[i];t!=-1;t=side[t].next){int j=side[t].j;if(f[i]!=f[j])++sum[f[j]];}}vector<int>vt;int flag=0;for(int i=1;i<=n;++i)if(sum[f[i]]==0){vt.push_back(i);if(flag==0)flag=f[i];else if(f[i]!=flag)flag=-1;}if(flag>0){sort(vt.begin(),vt.end());for(unsigned int i=0;i<vt.size();++i)cout<<vt[i]<<" ";}cout<<"0"<<endl;}
}