Problem: During the lunch break all n Berland State University students lined up in the food court. However, it turned out that the food court, too, has a lunch break and it temporarily stopped working.

Standing in a queue that isn't being served is so boring! So, each of the students wrote down the number of the student ID of the student that stands in line directly in front of him, and the student that stands in line directly behind him. If no one stands before or after a student (that is, he is the first one or the last one), then he writes down number 0 instead (in Berland State University student IDs are numerated from 1).

After that, all the students went about their business. When they returned, they found out that restoring the queue is not such an easy task.

Help the students to restore the state of the queue by the numbers of the student ID's of their neighbors in the queue.

Input

The first line contains integer n (2 ≤ n ≤ 2·105) — the number of students in the queue. 

Then n lines follow, i-th line contains the pair of integers ai, bi (0 ≤ ai, bi ≤ 106), where ai is the ID number of a person in front of a student and bi is the ID number of a person behind a student. The lines are given in the arbitrary order. Value 0 is given instead of a neighbor's ID number if the neighbor doesn't exist.

The ID numbers of all students are distinct. It is guaranteed that the records correspond too the queue where all the students stand in some order.

Output

Print a sequence of n integers x1, x2, ..., xn — the sequence of ID numbers of all the students in the order they go in the queue from the first student to the last one.

Examples

Input

4
92 31
0 7
31 0
7 141


Output

92 7 31 141 

Note

The picture illustrates the queue for the first sample.

<image>

Solution (in JAVA):

Solution:
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Comparator;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.PriorityQueue;
import java.util.StringTokenizer;


public class Main {

    
    private static boolean sameset(int a, int b, int[] uf) {
        
        return find(a,uf) == find(b,uf);
    }

    private static void union(int a, int b, int[] uf) {
        uf[find(a,uf)] = find(b,uf);
    }

    private static int find(int a, int[] uf) {
        if(a == uf[a])  return a;
        int root = find(uf[a],uf);
        uf[a] = root;
        return root;
    }

    private static void BFS(int i, int[][] G, int[][] path) {
       // System.out.println("source vertex "+i);
        int[] v = new int[G.length]; // current maximum dist in u---v path
        ArrayDeque<Integer> A = new ArrayDeque();
        A.add(i);
        while(A.isEmpty() == false){
            int u = A.pop();
            //System.out.println("for node "+u);
            for(int a=0;a<v.length;a++){
                if(G[u][a] > 0 && v[a]==0 && a!=i){//edge in MST, later make faster
                    //System.out.println(a+" is and edge from "+u);
                    if(G[u][a] > v[u]){
                        //System.out.println(" and it incrases the sub path max ");
                        v[a] = G[u][a];
                    }
                    else    v[a] = v[u];
                    path[i][a] = v[a];
                    path[a][i] = v[a];
                   // System.out.println("finally path from "+i+" to "+a+" is "+path[i][a]);
                    
                    A.add(a);
                }
            }
        }
    }

    private static int numd(int x) {
        Double xx = Double.parseDouble(String.valueOf(x));
        int y = (int) Math.log10(xx);
        return (y+1);
       
         
        
    }

    private static String primeFactor(int n, boolean[] x) {
        String ans = "";
        for(int i=2;i<x.length;i++){
            if(i*i > n) break;
            if(x[i]){
                //System.out.println("testing prome "+i);
                while(n!=1 && i*i <= n){
                    while(n%i==0){
                       // System.out.println(i+" can divide "+n);
                        if(ans.equals(""))  ans=String.valueOf(i);
                        else    ans+=" x "+i;
                        n/=i;
                    }
                    break;
                }
            }
        }
        if(n!=1){
           // System.out.println("Remainig "+n);
            if(ans.equals(""))  ans=String.valueOf(n);
            else    ans+=" x "+n;
        }
        return ans;
    }

    private static String solve(String s) {
        
        
        
        return null;
    }

    //counts the number of divisors using the fundamental theorem of arithmetic
    private static int getDivisorCount(int n) {
        
        int count = 1;
        
        int tmp = n;
        
        for(int i=2;i*i<=n;i=(i==2?3:i+2)){
            
            //System.out.println(i+" is odd");
            
            int pow = 0;
            
            while(n%i==0){
                pow+=1;
                n/=i;
            }
            
            if(pow != 0){
                ///System.out.println(i+" must be a prime");
                count*=(pow+1);
            }
        }
        
        if(n!=1){
            //System.out.println(n+" is the last prime factor");
            count*=2;
        }
        
        //System.out.println("number of divisors of "+tmp+" is "+count);
        return count;
    }

    private static long nchoosek(int n, int k) {
        
        long prod = 1;
        int j = 1;
        
        int st = Math.max(n-k, k)+1;
        int ed = Math.min(n-k, k);
        
        for(int i=st;i<=n;i++){
            for(;j<=ed;j++){
                if(prod%j==0)   prod/=j;
                else break;
            }
            prod*=i;
        }
        
        for(;j<=ed;j++){
            prod/=j;
        }
        
        return prod;
    }
    
    //related to extgcd problems
    private static boolean check() {
        //System.out.println(a+" "+b+" "+c1+" "+c2);
        if(n%ibgcd(a,b)!=0) {
           // System.out.println("not possible");
            return false;
        }
        
        extgcd(a,b);
        long gcd=0,m1=x,m2=y;
        gcd=d;
        m1*=(n/d);
        m2*=(n/d);
        a/=d;
        b/=d;
        
        double f1 = (m1/b);f1*=-1;
        double f2 = (m2/a);
        long le = (long) Math.ceil(f1);
        long re = (long) Math.floor(f2);
        if(le > re) return false;
        long cf=c1*b-c2*a;
        if(cf*le < cf*re){
        
            x = m1+b*le;
            y = m2-a*le;
        }else{
            x = m1+b*re;
            y = m2-a*re;
        }
        //System.out.println("upper and lower are "+le+" "+re);
        
        
        return true;
    }

    private static void extgcd(long a, long b) {
        
        if(b==0){
            x=1;y=0;d=a;return;
        }
        extgcd(b,a%b);
        long x1 = y;
        long y1 = x-(a/b)*y;
        x=x1;
        y=y1;
    }

    private static void floyd_cycle(int z, int I, int m, int x0) {
        
        int tor = func(z,I,m,x0);
        int har = func(z,I,m,tor); //one step ahead of tor
        //System.out.println("initial value for tor and har "+tor+" "+har);
        
        while(tor!=har){
            tor = func(z,I,m,tor);
            har = func(z,I,m,har);
            har = func(z,I,m,har);
            //System.out.println("tor and har "+tor+" "+har);
        }
        
        //at r-x%m now
        int x = 0;
        har = tor;
        tor = x0;
        
        while(har!=tor){
            
            tor = func(z,I,m,tor);
            har = func(z,I,m,har);
            x+=1;
            //System.out.println("findind x tor and har "+tor+" "+har);
        }
        
        //now at first reapting node
        int lam = 1;
        har = func(z,I,m,tor);
        
        while(har!=tor){
            har = func(z,I,m,har);
            lam+=1;
            //System.out.println("finding lam, tor and har "+tor+" "+har);
        }
        
       // return new Pair(z,lam);
    }

   private static int func(int z, int I, int m, int x0) {
        return ((z*x0)%m+I%m)%m;
    }

    private static void dfs(int a, int[][] d, int[] v,int[] p) {
        
        v[a] = 1;
        for(int i=0;i<v.length;i++){
            if(i!=a && d[i][a]!=0){
                if(v[i]==0){
                   // System.out.println("dfsing "+i);
                    p[i]=a;
                    dfs(i,d,v,p);
                }else if(p[a] != i && a<i){
                   // System.out.println(a+" and "+i+" causing cycle"+p[i]);
                    cycle=true;
                }
            }
        }
        
    }
    

    static class Node{
        
        int d=-1;
        long num;
        public Node(int a,long c){
            this.d = a;
            
            this.num = c;
            
        }
    }
    
    static class Edge{
        
        String d;
        int p;//ids of nodes
        int q;
        public Edge( String x1, int y1, int w){
            
            this.d = x1;
            this.p = y1;
            this.q = w;
        }
    }
    
    //simple sieve
    static boolean[] getPrimes(int n){
        
        boolean[] ret = new boolean[n+1];
        Arrays.fill(ret, true);
        
        ret[0] = ret[1] = false;
        
        for(int i=2;i*i <= n; i++){
            
            if(ret[i]){
                
                for(int j=i*i;j<=n;j+=i){
                    
                    ret[j]=false;
                }
            }
        }
        
        return ret;
    }
   
    static long ibgcd(long a, long b){
        
        while(b > 0){
            long r = a%b;
            a=b;
            b=r;
        }
        return a;
    }
    
    //for extgcd
    static long x,y,d; //output and gdc
    static long c1,c2,a,b,n; // inputs
    //static boolean[] p = getPrimes(5000001);
    
    static class Pair{
        String str;
        long cnt;
        public Pair(String a, long b){
            this.str=a;
            this.cnt=b;
        }
    }
    
    static boolean cycle = false;
    public static void main(String[] args) throws IOException {
        
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter bw = new BufferedWriter(new PrintWriter(System.out));
      
      int n = Integer.parseInt(br.readLine());
      
      HashMap<Integer,Integer> H = new HashMap();
      HashMap<Integer,Integer> right = new HashMap();
      HashMap<Integer,Integer> tab = new HashMap();
      
      ArrayList<Integer> A = new ArrayList();
      
      for(int i=0;i<n;i++){
          
          
          String[] _x = br.readLine().split(" ");
          
          int a = Integer.parseInt(_x[0]);
          int b = Integer.parseInt(_x[1]);
          
          H.put(a, b); //have an ID inbetwen
          
          if(!right.containsKey(b)){
              right.put(b, 1);
          }
          
          //set implementation
          if(!tab.containsKey(a) && a!=0){
              //System.out.println("adding "+a);
              A.add(a);
              tab.put(a, 1);
          }
          if(!tab.containsKey(b) && b!=0){
              //System.out.println("adding "+b);
              A.add(b);
              tab.put(b, 1);
          }
      }
      
      int first = -1;
      int second = -1;
      for(int i=0;i<n;i++){
          if(!right.containsKey(A.get(i))){
              first = A.get(i);
              break;
          }
      }
      second = H.get(0);
      
      //System.out.println(first+" "+second);
      int[] a = new int[n];
      a[0]=first;
      a[1]=second;
      
      int k = first;
      int in = 2;
      while(true){
          if(in >= n)   break;
          k=H.get(k);
          a[in]=k;
          in+=2;
      }
      
      k=second;
      in=3;
      while(true){
          if(in>=n) break;
          k=H.get(k);
          a[in]=k;
          in+=2;
      }
      
      for(int i=0;i<n;i++){
          bw.append(a[i]+" ");
      }
      bw.append("\n");
      
      bw.close();
    } 

}