#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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