#include<stdio.h>
#include<vector>
#include<string.h>
#define Nmax 10009

using namespace std;

int n1,n2,m,i,use[Nmax],j,x,y,nr,ok=1;
vector<int> a[Nmax],st(Nmax),dr(Nmax);

int cupleaza(int nod)
{
    use[nod]=1;
    for (vector<int>::iterator it=a[nod].begin();it!=a[nod].end();it++)
        if (!dr[*it] || (!use[dr[*it]] && cupleaza(dr[*it])))
        {
            st[nod]=*it;
            dr[*it]=nod;
            return 1;
        }
    return 0;
}

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

    scanf("%d%d%d",&n1,&n2,&m);
    for (i=1;i<=m;i++)
    {
        scanf("%d%d",&x,&y);
        a[x].push_back(y);
    }

    while (ok)
    {
        ok=0;
        memset(use,0,sizeof(use));
        for (i=1;i<=n1;i++)
        {
            if (st[i]) continue;
            if (cupleaza(i))
            {
                nr++;
                ok=1;
            }
        }
    }
    printf("%d\n",nr);
    for (i=1;i<=n1;i++)
        if (st[i]) printf("%d %d\n",i,st[i]);
}