#include<bits/stdc++.h>
using namespace std;
ifstream fin("cuplaj.in");
ofstream fout("cuplaj.out");
int sol,n,m,i,e,a,b,f[10010],st[10010],dr[10010];
vector<int> v[10010];
bool solve(int nod)
{
    f[nod]=1;
    for(auto it:v[nod]) if(st[it]==0)
    {
        dr[nod]=it;
        st[it]=nod;
        return 1;
    }
    for(auto it:v[nod]) if(!f[st[it]]&&solve(st[it]))
    {
        dr[nod]=it;
        st[it]=nod;
        return 1;
    }
    return 0;
}

int main()
{
    fin>>n>>m>>e;
    for(i=1;i<=e;i++)
    {
        fin>>a>>b;
        v[a].push_back(b);
    }
    bool ok=1;
    while(ok==1)
    {
        ok=0;
        memset(f,0,sizeof(f));
        for(i=1;i<=n;i++) if(dr[i]==0)  ok=max(ok,solve(i));
    }
    for(i=1;i<=n;i++) if(dr[i]) sol++;
    fout<<sol<<"\n";
    for(i=1;i<=n;i++) if(dr[i]) fout<<i<<" "<<dr[i]<<"\n";
    return 0;
}