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

const int N = 10010;

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

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

int zgood(int y)
{
    if ( r[y] == 0 ) return 1;
    if ( mark[r[y]] == 1 ) return 0;

    int x = r[y];
    mark[x] = 1;

    for (int i=0;i<int(v[x].size());++i)
    {
        int y2 = v[x][i];
        if ( y2 != y )
            if( zgood(y2) )
            {
                l[x] = y2;
                r[y2] = 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 co = 0;
    int better = 1;
    while ( better )
    {
        better = 0;
        memset(mark,0,sizeof(mark));
        for (int x=1;x<=n;++x)
            if ( l[x] == 0 )
                for (int j=0;j<int(v[x].size());++j)
                {
                    int y = v[x][j];
                    if ( zgood(y) )
                    {
                        l[x] = y;
                        r[y] = x;
                        //for (int i=1;i<=n;++i) cerr<<l[i]<<' '; cerr<<'\n';
                        //for (int i=1;i<=m;++i) cerr<<r[i]<<' '; cerr<<'\n';
                        better = 1;
                        ++co;
                        break;
                    }
                }
    }
    G<<co<<'\n';
    for (int i=1;i<=n;++i)
        if ( l[i] )
            G<<i<<' '<<l[i]<<'\n';
}