Grade3

#include <iostream>
using namespace std;

int GE[101],GI[101],n, m, gasit;
int sol[101], ls;
int main()
{
    cin>>n>>m;
    for(int i=1; i<=m; i++)
    {
        int x,y;
        cin>>x>>y;
        GE[x]++;
        GI[y]++;
    }
    for(int i=1; i<=n; i++)
        if(GE[i]<GI[i])
        {
                gasit++;
                sol[++ls]=i;
        }
    cout<<gasit<<'\n';
    for(int i=1; i<=ls; ++i)
        cout<<sol[i]<<" ";
    return 0;
}