#include <stdio.h>
#include <vector>
#include <algorithm>
using namespace std;
#define pb push_back
#define maxn 10001
int n,m,e,i,x,y,ch=1,nr;
vector<int> g[maxn];
int l[maxn],r[maxn],v[maxn];
int leg(int k)
{
    if(v[k]) return 0;
    v[k]=1;
    for (int i=0;i<g[k].size();++i)
        if (!r[g[k][i]]){
           l[k]=g[k][i];
           r[g[k][i]]=k;
           return 1;
           }
    for (int i=0;i<g[k].size();++i)
        if (leg(r[g[k][i]])){
           l[k]=g[k][i];
           r[g[k][i]]=k;
           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);
        g[x].pb(y);
        }
    for (;ch;){
        ch=0;
        memset(v,0,sizeof(v));
        for (i=1;i<=n;++i)
            if (!l[i])ch|=leg(i);
        }
    for (i=1;i<=n;++i)
        if(l[i])nr++;
    printf("%d\n",nr);
    for (i=1;i<=n;++i)
        if (l[i]) printf("%d %d\n",i,l[i]);
    return 0;
}