#include <bits/stdc++.h>

using namespace std;

int n,m,e,t;
vector<int> v[10010];
int viz[10010],dr[10010],st[10010];

bool pairup(int x){
    int i,nr;
    if (viz[x]) return 0;
    viz[x]=1;
    for (i=0,nr=v[x].size();i<nr;i++){
        if (dr[v[x][i]]==0){
            st[x]=v[x][i];
            dr[v[x][i]]=x;
            return 1;
        }
    }
    for (i=0,nr=v[x].size();i<nr;i++)
    if (pairup(dr[v[x][i]])){
        st[x]=v[x][i];
        dr[v[x][i]]=x;
        return 1;
    }
    return 0;
}

int main()
{
    freopen("cuplaj.in","r",stdin);
    freopen("cuplaj.out","w",stdout);

    int ok=1,i,x,y;
    scanf("%d%d%d",&n,&m,&e);
    for (i=1;i<=e;i++){
        scanf("%d%d",&x,&y);
        v[x].push_back(y);
    }

    while (ok){
        ok=0;
        memset(viz,0,sizeof(viz));
        for (i=1;i<=n;i++){
            if (!st[i]) ok|=pairup(i);
        }
    }
    for (i=1;i<=n;i++)
        if (st[i]) t++;
    printf("%d\n",t);
    for (i=1;i<=n;i++)
        if (st[i]) printf("%d %d\n",i,st[i]);
    return 0;
}