#include<stdio.h>
#define Nmx 10005
#include<vector>

using namespace std;

int n,m,T,viz[Nmx],r[Nmx],l[Nmx];
vector<int> G[Nmx];

void citire()
{
    scanf("%d%d%d",&n,&m,&T);
    int x,y;
    for(int i=1;i<=T;++i)
    {
        scanf("%d%d",&x,&y);
        G[x].push_back(y);
    }
}

int pairup(int nod)
{
    if(viz[nod])
        return 0;
    viz[nod]=1;
    for(int i=0;i<G[nod].size();++i)
        if(!r[G[nod][i]])
        {
            r[G[nod][i]]=nod;
            l[nod]=G[nod][i];
            return 1;
        }
    for(int i=0;i<G[nod].size();++i)
        if(pairup(r[G[nod][i]]))
        {
            r[G[nod][i]]=nod;
            l[nod]=G[nod][i];
            return 1;
        }
    return 0;
}

void solve()
{
    int ok,cuplaj=0;
    do
    {
        ok=0;
        memset(viz,0,sizeof(viz));
        for(int i=1;i<=n;++i)
            if(!l[i]&&pairup(i))
            {
                cuplaj++;
                ok=1;
            }
    }while(ok);
    printf("%d\n",cuplaj);
    for(int i=1;i<=n;++i)
        if(l[i])
            printf("%d %d\n",i,l[i]);
}

int main()
{
    freopen("cuplaj.in","r",stdin);
    freopen("cuplaj.out","w",stdout);
    citire();
    solve();
    return 0;
}