#include<bits/stdc++.h>
#define ll long long
#define pb push_back
#define ve vector
#define endl '\n'
#define itn int
#define AC return 0
#define len length
#define max(a,b) ((a)>(b)?(a):(b))
#define min(a,b) ((a)<(b)?(a):(b))
using namespace std;
const itn N=5e2+5;
ve<int> edge[N];
int indg[N],outdg[N],m,n,s,t;
bool vis[N];
void add(int u,int v){
	edge[u].pb(v);
	indg[v]++;
	outdg[u]++;
}
stack<int> ans;
void dfs(int u){
	for(int i=0;i<edge[u].size();i++){
		if(edge[u][i]!=-1){
			int v=edge[u][i];
			edge[u][i]=-1;
			dfs(v);
		}
	}
	ans.push(u);
}
int main()
{
    ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
    //begin
    cin>>m;
    for(int i=1;i<=m;i++){
    	int u,v;
    	cin>>u>>v;
    	n=max(n,max(u,v));
    	add(u,v);
	}
	for(itn i=1;i<=n;i++){
		if(indg[i]-outdg[i]==1){
			if(t){
				cout<<"No";
				AC;
			}
			t=i;
		}
		if(outdg[i]-indg[i]==1){
			if(s){
				cout<<"No";
				AC;
			}
			s=i;
		}
	}
	for(int i=1;i<=n;i++)
		sort(edge[i].begin(),edge[i].end());
	s=s?s:1;
	dfs(s);
	while(!ans.empty()){
		cout<<ans.top()<<endl;
		ans.pop();
	}
	//end
    AC;
}