#include<vector>
#include<cstdio>
#include<cstring>
#define NMAX 10005
using namespace std;
vector<int>v[NMAX];
int L[NMAX],R[NMAX],viz[NMAX];
int n,m,i,e,nr,x,y;
int cupleaza(int nod)
{
    vector<int>::iterator it;
    viz[nod]=1;
    for (it=v[nod].begin();it!=v[nod].end();++it)
    {
        if (R[*it]==0)
        {
            L[nod]=*it;
            R[*it]=nod;
            return 1;
        }
    }
    for (it=v[nod].begin();it!=v[nod].end();++it)
    {
        if (viz[R[*it]]==0 && cupleaza(R[*it]))
        {
            L[nod]=*it;
            R[*it]=nod;
            return 1;
        }
    }
    return 0;

}
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);
    }
    int ok=0;
    do
    {
        ok=1;
        memset(viz,0,sizeof(viz));
        for (i=1;i<=n;++i)
            if (L[i]==0 && cupleaza(i)) ok=0;
    }while(ok==0);
    for (i=1;i<=n;++i)
        if (L[i]!=0) ++nr;
    printf("%d\n",nr);
    for(i=1;i<=n;++i)
    {
        if (L[i]!=0) printf("%d %d\n",i,L[i]);
    }
    return 0;
}