#include <bits/stdc++.h>
using namespace std;
#define LMAX 10005
vector<int> G[LMAX];
int l[LMAX],r[LMAX],viz[LMAX];
bool pair_up(int nod){
    if(viz[nod])
        return 0;
    viz[nod]=1;
    for(auto it : G[nod])
        if(!r[it]){
            l[nod]=it;
            r[it]=nod;
            return 1;
        }
    for(auto it : G[nod])
        if(pair_up(r[it])){
            l[nod]=it;
            r[it]=nod;
            return 1;
        }
    return 0;
}
int main(){
    freopen("cuplaj.in", "r", stdin);
    freopen("cuplaj.out", "w", stdout);
    int n,m,ct_edges;
    scanf("%d %d %d",&n,&m,&ct_edges);
    while(ct_edges--){
        int from,to;
        scanf("%d %d",&from,&to);
        G[from].push_back(to);
    }
    bool ok=0;
    do{
        ok=0;
        memset(viz,0,sizeof(viz));
        for(int i=1;i<=n;++i)
            if(!l[i]){
                if(pair_up(i))
                    ok=1;
            }
    }while(ok);
    int ans=0;
    for(int i=1;i<=n;++i)
        if(l[i]>0)
            ++ans;
    printf("%d\n",ans);
    for(int i=1;i<=n;++i)
        if(l[i]>0)
            printf("%d %d\n",i,l[i]);
    return 0;
}