#include <cstdio>
#include <vector>
using namespace std;
vector <int> v[10004],v1[10004],s;
int n,m,e,i,x,y,nr1,nr[10004],a[10004],b[10004],k,j,h,h1,q;
bool ok,c[10004];
void cupleaza (int x)
{
    int z,h,i;
    z=v[x].size();
    for (k=0;k<=(z-1);k++)
    {
        q=b[v[x][k]];
        if (nr[q]>0)
        {
            for (j=0;j<=(v[q].size()-1);j++)
            {
                if (a[v[q][j]]==0)
                    break;
            }
            if (a[v[q][j]]==0)
            {
                a[v[q][j]]=1;
                b[v[q][j]]=q;
                b[v[x][k]]=x;
                for (h=0;h<=(v1[v[q][j]].size()-1);h++)
                    nr[v1[v[q][j]][h]]--;
            }
            ok=true;
            nr1++;
            return;
        }
        else
        {
            cupleaza (b[v[x][k]]);
            if (ok==true)
                b[v[x][k]]=x;
            return;
        }
    }
}
int main()
{
    freopen ("cuplaj.in","r",stdin);
    freopen ("cuplaj.out","w",stdout);
    scanf ("%d %d %d", &n, &m, &e);
    for (i=1;i<=e;i++)
    {
        scanf ("%d %d", &x, &y);
        v[x].push_back(y);
        v1[y].push_back(x);
        nr[x]++;
    }
    nr1=0;
    for (i=1;i<=n;i++)
    {
        ok=false;
        k=v[i].size();
        for (j=0;j<=(k-1);j++)
        {
            if (a[v[i][j]]==0)
            {
                a[v[i][j]]=1;
                b[v[i][j]]=i;
                ok=true;
                nr1++;
                for (h=0;h<=(v1[v[i][j]].size()-1);h++)
                    nr[v1[v[i][j]][h]]--;
                break;
            }
        }
        if (ok==false)
            s.push_back(i);
    }
    h=s.size();
    ok=true;
    while (ok==true && k>=1)
    {
        ok=false;
        for (i=0;i<=(h-1);i++)
        {
            cupleaza(s[i]);
            if (ok==true)
                break;
        }
    }
    printf ("%d\n", nr1);
    for (i=1;i<=m;i++)
    {
        if (b[i]!=0)
            printf ("%d %d\n", b[i], i);
    }
    return 0;
}