#include <bits/stdc++.h>
#define Nmax 10005
using namespace std;
ifstream fin ("cuplaj.in");
ofstream fout ("cuplaj.out");
vector <int> v[2*Nmax];
int viz[2*Nmax], ma[2*Nmax], ok, n, m, e, k;
int dfs(int nod)
{
    viz[nod]=1;
    for(auto it:v[nod])
        if(!ma[it] || (!viz[ma[it]] && dfs(ma[it])))
        {
            ma[it]=nod;
            ma[nod]=it;
            return 1;
        }
    return 0;
}
int main()
{
    fin >> n >> m >> e;
    for(int i=1;i<=e;i++)
    {
        int x, y;
        fin >> x >> y;
        v[x].push_back(y+n);
        v[y+n].push_back(x);
    }
    ok=1;
    while(ok)
    {
        ok=0;
        memset(viz, 0, sizeof(viz));
        for(int i=1;i<=n;i++)
            if(!viz[i] && !ma[i] && dfs(i))
                ok=1;
    }
    for(int i=1;i<=n;i++)
        if(ma[i])
            k++;
    fout << k << '\n';
    for(int i=1;i<=n;i++)
        if(ma[i])
            fout << i << ' ' << ma[i]-n << '\n';
    return 0;
}