#include <bits/stdc++.h>

using namespace std;
const int NMAX=10001;

ifstream f("cuplaj.in");
ofstream g("cuplaj.out");
vector<int> G[NMAX];
int N, M, E,
    L[NMAX], R[NMAX],
    maxMatch;

bool viz[NMAX];

void citire()
{
    int x,y;
    f>>N>>M>>E;
    while(E--)
    {
        f>>x>>y;
        G[x].push_back(y);
    }
}

bool DFS(int x)
{
    if(viz[x])return 0;
    viz[x]=1;
    for(auto &y: G[x])
        if(!R[y]||DFS(R[y]))
        {
            L[x]=y;
            R[y]=x;
            return 1;
        }
}
void HK()
{
    bool wasChanged=1;
    int i;
    while(wasChanged)
    {
        wasChanged=0;
        for(i=1; i<=N; i++)
            viz[i]=0;
        for(i=1; i<=N; i++)
        {
            if(!L[i]&&DFS(i))
            {
                wasChanged = 1;
                maxMatch++;
            }
        }
    }
}

int main()
{
    citire();
    HK();
    g<<maxMatch<<'\n';
    for(int i=1; i<=N; i++)
    {
        if(L[i]!=0)
            g<<i<<' '<<L[i]<<'\n';
    }
    return 0;
}