#include <bits/stdc++.h>
using namespace std;
vector<int> g[200001];
vector<int> topo;
bool seen[2000001];
void dfs(int x){
	if (!seen[x]){
		seen[x]=true; 
		for (int edge:g[x]){
			dfs(edge);
		}
		topo.push_back(x);

	}
}

int main() {
	int n,m;
	cin>>n>>m;
	for (int i=0; i<m;i++){
		int x,y;
		cin>>x>>y;
		g[x].push_back(y);
	}
	for (int i=1; i<=n;i++){
		if (!seen[i]){
			dfs(i);
		}
	}
	reverse(topo.begin(), topo.end());
	cout<<1<<endl; 
	for (int x:topo) cout<<x<<" "; 
}