#include <bits/stdc++.h>
#define Dim 10001
using namespace std;
ifstream f("cuplaj.in");
ofstream g("cuplaj.out");
int L,R,M,right_to_left[Dim],x,y,left_to_right[Dim],viz[Dim],ans;

vector < int > V[Dim];

bool Hopcroft(int nod)
{
    if(viz[nod]) return false;
    viz[nod]=1;
    for(unsigned int i=0;i<V[nod].size();i++)
    {
        int vecin=V[nod][i];
        if( right_to_left[vecin] == 0 )
        {
            right_to_left[vecin]=nod;
            left_to_right[nod]=vecin;
            return true;
        }
    }
    for(unsigned int i=0;i<V[nod].size();i++)
    {
        int vecin=V[nod][i];
        if( Hopcroft( right_to_left[vecin] ) )
        {
            right_to_left[vecin]=nod;
            left_to_right[nod]=vecin;
            return true;
        }
    }
    return false;
}

int main()
{
    f>>L>>R>>M;
    for(int i=1;i<=M;i++)
    {
        f>>x>>y;
        V[x].push_back(y);
    }

    bool ok=1;
    while(ok)
    {
        ok=0;
        for(int i=1;i<=L;i++) viz[i]=0;
        for(int i=1;i<=L;i++)
        if( left_to_right[i]==0 )
        {
            bool up=Hopcroft(i);
            if(up)
            {
                ok=1;
                ans++;
            }
        }
    }
    g<<ans<<'\n';
    for(int i=1;i<=L;i++)
    if( left_to_right[i] ) g<<i<<" "<<left_to_right[i]<<'\n';


    return 0;
}