#include <iostream>
#include <vector>
#include <limits>
#include <queue>
#include <algorithm>
using namespace std;

typedef pair<int, int> parint;
typedef vector< vector<parint> > graph;
const int infinit = numeric_limits<int>::max();

void dijkstra(const graph& g, int u, vector<int>& d, vector<int>& p) {
	int n = g.size();
	vector<bool> visto(n, false);
	d[u] = 0;
	p[u] = 0;
	queue<parint> q;
	q.push(parint(u,0));
	while(not q.empty()) {
		int v = (q.front()).first;
		q.pop();
		if(not visto[v]) {
			visto[v] = true;
			for(int i = 0; i < (int)g[v].size(); ++i) {
				int w = g[v][i].first; //vertice adj
				int r = g[v][i].second;
				//if(not visto[w]) {
					if(d[w] > d[v] + r) {
						d[w] = d[v] + r;
						p[w] = v;
						q.push(parint(w,d[w]));
					}
				//}
			}
		}
	}
}

void escribir(const vector<int>& c, int v0, int vf) {
    if(v0 != vf) {
        escribir(c,v0,c[vf]);
        cout << c[vf] << " ";
    }

}

bool comp(const parint& a, const parint& b) {
	return a.first < b.first;
}

int main() {
	int n, m;
	while(cin >> n >> m) {
		graph g(n);
		for(int i = 0; i < m; ++i) {
			int u, v;
			cin >> u >> v;
			g[u].push_back(parint(v,1));
		}
		//ordenem les adjacencies abans de fer el dijkstra
		for(int i = 0; i < n; ++i) {
			sort(g[i].begin(), g[i].end(), comp);
		}
		vector<int> dist(n, infinit);
		vector<int> path(n, -1);
		dijkstra(g, 0, dist, path);
		//0 el vertex inicial
		//a path tindre el cami mes curt
		escribir(path, 0, n-1);
		cout << n-1 << endl;
	}
}