#include <cstdio>
#include <vector>
using namespace std;
vector <int> v[10005];
int marked[10005],l[10005],r[10005],n,m,e;
bool cupleaza(int node){
marked[node]=1;
for(auto it:v[node])
if(!r[it]){
    l[node]=it;
    r[it]=node;
    return 1;
}
for(auto it:v[node])
if(!marked[r[it]] && cupleaza(r[it])){
    l[node]=it;
    r[it]=node;
    return 1;
}
return 0;
}
int i,x,y,nr;
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);
    }
    bool done=1;
    while(done){
            done=0;
    for(i=1;i<=n;i++)marked[i]=0;
    for(i=1;i<=n;i++)
        if(!l[i] && !marked[i])
        done|=cupleaza(i);
    }
    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;
}