#include <bits/stdc++.h>
#define ll long long
#define mp make_pair
using namespace std;
vector <int> taba[50001];
vector <int> tabb[50001];
char viz[50001];
vector <pair <int,int> > order;
void BFS(int nodx , int val){
    queue <pair <int,int> > bf;
    bf.push(mp(nodx,val));
    while(!bf.empty()){
        pair <int,int> pr = bf.front();
        viz[pr.first] = 1;
        order.push_back(pr);
        for(int i = 0 ; i < taba[pr.first].size() ; i++){
            if(viz[taba[pr.first][i]]!=1)
            bf.push(mp(taba[pr.first][i],pr.second + 1));
        }
        for(int i = 0 ; i < tabb[pr.first].size() ; i++){
            if(viz[tabb[pr.first][i]]!=1)
            bf.push(mp(tabb[pr.first][i],pr.second - 1));
        }
        bf.pop();
    }
}
bool cmp (pair <int,int> x , pair <int,int> y){
    return x.second < y.second;
}
ifstream fin ("sortare.in");
ofstream fout("sortare.out");
int main()
{
    int n , m;
    fin >> n >> m;
    int a , b;
    for(int i = 1 ; i <= m ; i++){
        fin >> a >> b;
        taba[a].push_back(b);
        tabb[b].push_back(a);
    }
    BFS(n,0);
    sort(order.begin(),order.end() , cmp);
    for(int i = 0 ; i < order.size() ; i++){
        fout << order[i].first << " ";
    }
}