#include <bits/stdc++.h>
using namespace std;
ifstream fin("cuplaj.in");
ofstream fout("cuplaj.out");
#define NMAX 10005
int n, m, e, x, y, viz[NMAX], dr[NMAX], st[NMAX];
vector<int> v[NMAX];
int pairup(int nod)
{
    if (viz[nod] == 1)
        return 0;
    viz[nod] = 1;
    for (int i=0;i<v[nod].size();i++){
        int vec = v[nod][i];
        if (!st[vec] || pairup(st[vec])){
            st[vec] = nod;
            dr[nod] = vec;
            return 1;
        }
    }
    return 0;
}
int main() {
    fin >> n >> m >> e;
    for (int i=1;i<=e;i++){
        fin >> x >> y;
        v[x].push_back(y);
    }
    bool ok = true;
    while(ok){
        memset(viz, 0, sizeof(viz));
        ok = false;
        for (int i=1;i<=n;i++){
            if (!dr[i] && pairup(i))
                ok = true;
        }
    }
    int ans = 0;
    for (int i=1;i<=n;i++){
        if (dr[i])
            ans ++;
    }
    fout << ans << '\n';
    for (int i=1;i<=n;i++){
        if (dr[i]){
            fout << i << ' ' << dr[i] << '\n';
        }
    }
    return 0;
}