#include <bits/stdc++.h>

using namespace std;
ifstream fin("cuplaj.in");
ofstream fout("cuplaj.out");

int n,m,e,x,y,viz[10001],cl[10001],cr[10001];
vector<int> l[10001], r[10001];

int dfs(int nod)
{
    viz[nod]=1;
    for (auto v: l[nod])
    {
        if (cr[v]==0||(!viz[cr[v]]&&dfs(cr[v])))
        {
            cr[v]=nod;
            cl[nod]=v;
            return true;
        }
    }
    return false;
}

int main()
{
    ios_base::sync_with_stdio(false);
    fin>>n>>m>>e;
    for (int i=1;i<=e;i++)
    {
        fin>>x>>y;
        l[x].push_back(y);
        r[y].push_back(x);
    }
    int ok=1;
    while (ok)
    {
        ok=0;
        memset(viz, 0, sizeof(viz));
        for (int i=1;i<=n;i++)
        {
            if (viz[i]==0&&!cl[i])
                ok+=dfs(i);
        }
    }
    int ans=0;
    for (int i=1;i<=n;i++)
        if (cl[i])
        ans++;
    fout<<ans<<endl;
    for (int i=1;i<=n;i++)
        if (cl[i])
        fout<<i<<" "<<cl[i]<<'\n';
    return 0;
}