///circular
//unordered_
#include <bits/stdc++.h>
#define MOD 1000000007
using namespace std;
ifstream fin("cuplaj.in");
ofstream fout("cuplaj.out");
int i,n,m,e,fro[100010],to[100010],x,y,cn;
bool f[100010];
vector <int> v[100010];

bool cup(int k)
{
    if(f[k])
        return false;
    f[k]=1;
    for(auto it : v[k])
        if(fro[it]==0 || cup(fro[it]))
        {
            to[k]=it;
            fro[it]=k;
            return true;
        }
    return false;
}
int main()
{
    cin.tie(0);
    cout.tie(0);
    fin>>n>>m>>e;
    for(i=1; i<=e; i++)
    {
        fin>>x>>y;
        v[x].push_back(y);
    }
    bool change=1;
    while(change)
    {
        change=0;
        for(i=1; i<=n; i++)
            if(to[i]==0)
            {
                change|=cup(i);
                cn++;
            }
        memset(f,0,sizeof(f));
    }
    fout<<cn/2<<'\n';
    for(i=1; i<=n; i++)
        if(to[i])
            fout<<i<<" "<<to[i]<<'\n';
    return 0;
}