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

int n,m,nr,z[10005],l[10005],used[10005],total;

vector <int > g[10005];

bool cuplaj(int nod)
{
    if (used[nod])
        return false;
    used[nod]=true;
    for (vector < int > :: iterator it=g[nod].begin(); it!=g[nod].end(); ++it)
        if (!z[*it])
        {
            z[*it]=nod;
            l[nod]=*it;
            return true;
        }
    for (vector < int > :: iterator it=g[nod].begin(); it!=g[nod].end(); ++it)
        if (cuplaj(z[*it]))
        {
            z[*it]=nod;
            l[nod]=*it;
            return true;
        }
    return false;
}
void citire()
{
    freopen("cuplaj.in","r",stdin);
    freopen("cuplaj.out","w",stdout);
    scanf("%d%d%d",&n,&m,&nr);
    for (int i=1; i<=nr; ++i)
    {
        int x,y;
        scanf("%d%d",&x,&y);
        g[x].push_back(y);
    }
}
void solve()
{
    for (int i=1; i<=n; ++i)
        for (vector < int > :: iterator it=g[i].begin(); it!=g[i].end(); ++it)
            if (!z[*it])
            {
                z[*it]=i;
                l[i]=*it;
                break;
            }
    int ok=1;
    while (ok)
    {
        ok=0;
        memset(used,0,sizeof(used));
        for (int i=1; i<=n; ++i)
        {
            if (!l[i])

                ok+=cuplaj(i);
        }
    }
    for (int i=1; i<=n; ++i)
        if (l[i])
            ++total;
    printf("%d\n",total);
    for (int i=1; i<=n; ++i)
        if (l[i])
            printf("%d %d\n",i,l[i]);
}
int main()
{
    citire();
    solve();
    return 0;
}