#include <iostream>
#include <cstdio>
#include <vector>
#include <bitset>

using namespace std;

vector <int> g[10005];
int l[10005], r[10005];
bitset <10005> viz;
int n,m,e,x,y;

bool cuplaj(int nod){
    if(viz[nod])
        return 0;
    viz[nod]=1;
    for(int i : g[nod])
        if(!r[i]){
            r[i]=nod;
            l[nod]=i;
            return 1;
        }
    for(int i : g[nod])
        if(cuplaj(r[i])){
            l[nod]=i;
            r[i]=nod;
            return 1;
        }
    return 0;
}

int main()
{
    freopen("cuplaj.in","r",stdin);
    freopen("cuplaj.out","w",stdout);

    scanf("%d%d%d", &n,&m,&e);
    for(int i=0;i<e;++i){
        scanf("%d%d",&x,&y);
        g[x].push_back(y);
    }

    bool ok=1;
    while(ok){
        ok=0;
        viz.reset();
        for(int i=1;i<=n;++i)
            if(!l[i])
                ok|=cuplaj(i);
    }

    int sol=0;
    for(int i=1;i<=n;++i)
        if(l[i]>0)
            ++sol;
    cout<<sol<<"\n";
    for(int i=1;i<=n;++i)
        if(l[i]>0)
            cout<<i<<" "<<l[i]<<"\n";

    return 0;
}