#include <cstdio>
#include <vector>
#include <bitset>

using namespace std;

const int nmx = 10002;

int n,m,l,st[nmx],dr[nmx];
vector <int> g[nmx];
bitset <nmx> viz;

void citire()
{
    scanf("%d %d %d", &n,&m, &l);
    for(int i = 1; i <= l; ++i)
    {
        int nod1,nod2;
        scanf("%d %d", &nod1, &nod2);
        g[nod1].push_back(nod2);
    }
}

bool uneste(int nod)
{
    if(viz[nod])
        return false;
    viz[nod] = true;
    for(vector<int>::iterator it = g[nod].begin(); it != g[nod].end(); ++it)
        if(not st[*it])
        {
            dr[nod] = *it;
            st[*it] = nod;
            return true;
        }
    for(vector<int>::iterator it = g[nod].begin(); it != g[nod].end(); ++it)
        if(uneste(st[*it]))
        {
            dr[nod] = *it;
            st[*it] = nod;
            return true;
        }
    return false;
}

void cuplare()
{
    bool ok = 1;
    while(ok)
    {
        ok = 0;
        viz.reset();
        for(int i = 1; i <= n; ++i)
            if(not dr[i])
                ok |= uneste(i);
    }
}

void afish()
{
    int total = 0;
    for(int i = 1; i <= n; ++i)
        if(dr[i])
            ++ total;
    printf("%d\n", total);
    for(int i = 1; i <= n; ++i)
        if(dr[i])
            printf("%d %d\n", i, dr[i]);
}

int main()
{
    freopen("cuplaj.in", "r", stdin);
    freopen("cuplaj.out", "w", stdout);
    citire();
    cuplare();
    afish();
    return 0;
}