#include <bits/stdc++.h>
#define maxN 260
using namespace std;
bool seen[maxN];
vector<int> path;
vector<int> v[maxN];
int _left[maxN],_right[maxN];
bool edges[maxN][maxN];
int n,m,i,j,x,y;
bool pairup(int nod)
{
    if(seen[nod])
        return false;
    seen[nod]=true;

    for(auto it:v[nod])
        if(!_right[it])
        {
            _right[it]=nod;
            _left[nod]=it;
            return true;
        }

    for(auto it:v[nod])
        if(pairup(_right[it]))
        {
            _right[it]=nod;
            _left[nod]=it;
            return true;
        }
    return false;
}
void createPath(int nod)
{
    path.push_back(nod);
    if(_left[nod])
        createPath(_left[nod]);
}
int main()
{
    freopen("strazi.in","r",stdin);
    freopen("strazi.out","w",stdout);
    scanf("%d %d",&n,&m);
    for(i=1;i<=m;i++){
        scanf("%d %d",&x,&y);
        edges[x][y]=true;
        v[x].push_back(y);
    }

    bool ok=true;
    int maxmatch=0;
    while(ok)
    {
        ok=false;
        memset(seen,false,sizeof(seen));
        for(i=1;i<=n;i++)
            if(!_left[i])
                ok|=pairup(i);
    }
    for(i=1;i<=n;i++)
        if(_left[i])
            maxmatch++;
    printf("%d\n",n-1-maxmatch);
    for(i=1;i<=n;i++)
        if(!_right[i])
            createPath(i);

    for(i=0;i<path.size()-1;i++)
        if(!edges[path[i]][path[i+1]])
            printf("%d %d\n",path[i],path[i+1]);

    for(auto it:path)
        printf("%d ",it);
    return 0;
}