#include <fstream>
#include <iostream>
#include <cstring>
#include <vector>
using namespace std;

ifstream F("cuplaj.in");
ofstream G("cuplaj.out");

const int N = 10010;

int n,m,e,mk[N],l[N],r[N];
vector<int> v[N];

bool good(int x)
{
    if ( x == 0 ) return 1;
    mk[x] = 1;
    for (int i=0;i<int(v[x].size());++i)
    {
        int y = v[x][i];
        if ( !mk[r[y]] )
            if ( good(r[y]) )
            {
                l[x] = y;
                r[y] = x;
                return 1;
            }
    }
    return 0;
}

int main()
{
    F>>n>>m>>e;
    for (int i=1,x,y;i<=e;++i)
    {
        F>>x>>y;
        v[x].push_back(y);
    }
    int ans = 0;
    bool ok = 1;
    while ( ok )
    {
        ok = 0;
        memset(mk,0,sizeof(mk));
        for (int i=1;i<=n;++i)
            if ( !mk[i] && l[i] == 0 )
                if ( good(i) )
                {
                    ++ans;
                    ok = 1;
                }
    }
    G<<ans<<'\n';
    for (int i=1;i<=n;++i)
        if ( l[i] )
            G<<i<<' '<<l[i]<<'\n';
}