#include <bits/stdc++.h>
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#pragma GCC optimize("fast-math")
using namespace std;
ifstream fin("cuplaj.in");
ofstream fout("cuplaj.out");
int e;
short n,m;
short l[10005],r[10005];
vector<short> muchii[10005];
bool use[10005];
bool pairup(short nod)
{
    if(use[nod])
        return 0;
    use[nod]=1;
    for(short i:muchii[nod])
        if(r[i]==0)
        {
            l[nod]=i;
            r[i]=nod;
            return 1;
        }
    for(short i:muchii[nod])
        if(pairup(r[i]))
        {
            l[nod]=i;
            r[i]=nod;
            return 1;
        }
    return 0;
}
int main()
{
    ios_base::sync_with_stdio(false);
    fin.tie(0);
    fin>>n>>m>>e;
    for(short i=1;i<=e;i++)
    {
        short a,b;
        fin>>a>>b;
        muchii[a].push_back(b);
    }
    bool ok=0;
    do
    {
        ok=0;
        for(short i=1;i<=n;i++)
            use[i]=0;
        for(short i=1;i<=n;i++)
            if(l[i]==0)
                ok|=pairup(i);
    }while(ok);
    short ans=0;
    for(short i=1;i<=n;i++)
        if(l[i]!=0)
            ans++;
    fout<<ans<<'\n';
    for(short i=1;i<=n;i++)
        if(l[i]!=0)
            fout<<i<<' '<<l[i]<<'\n';
    return 0;
}