#include <bits/stdc++.h>

using namespace std;

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

int n, m, k;
vector<int>v[10005];
int rgt[10005];
int lft[10005];
int vis[10005];

bool Cuplaj(int i)
{
    //cout << i << " " << rgt[i] << " " << vis[i] << "\n";

    if(vis[i])
        return false;
    vis[i] = 1;
    for(auto x: v[i])
    {
        if(lft[x] == 0)
        {
            rgt[i] = x;
            lft[x] = i;
            return true;
        }
    }
    for(auto x: v[i])
    {
        if(Cuplaj(lft[x]))
        {
            rgt[i] = x;
            lft[x] = i;
            return true;
        }
    }
    return false;

}


void Citire()
{
    int x, y;
    fin >> n >> m >> k;
    for(int i = 1; i <= k; i++)
    {
        fin >> x >> y;
        v[x].push_back(y);
    }
}

int main()
{
    int answer = 0;
    bool hasPath = true;

    Citire();

    while(hasPath)
    {
        for(int i = 1; i <= n; i++)
            vis[i] = 0;
        hasPath = false;
        for(int i = 1; i <= n; i++)
        {
            if(rgt[i] == 0 && Cuplaj(i))
            {
                answer++;
                hasPath = true;
            }
           // cout << "--------------\n";
        }
    }
    fout << answer << "\n";
    for(int i = 1; i <= n; i++)
        if(rgt[i])
            fout << i << " " << rgt[i] << "\n";

    return 0;
}