#include<iostream>
#include<vector>
using namespace std;
const int n=6;
vector<int>q;
int visited[n]={0};
void dfs(vector<int>arr[],int s)
{
for(int i=0;i<arr[s].size();i++)
{
if(visited[arr[s][i]]==0)
{
visited[arr[s][i]]=1;
dfs(arr,arr[s][i]);
q.push_back(arr[s][i]);
}
}
}
int main()
{ int u,v;
vector<int>arr[n];
for(int i=0;i<n ;i++)
{
cin>>v>>u;
arr[v].push_back(u);
}
dfs(arr,0);
for(int i=0;i<n;i++)
{
cout<<q[i]<<" ";
}
}
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