#include <cstdio>
#include <vector>

using namespace std;

vector<int> v[10010];
int vaz[10010],cup1[10010],cup2[10010];

int cupleaza(int nod)
{
    if(vaz[nod]==1) return 0;
    vaz[nod]=1;
    for(int i=0;i<v[nod].size();i++)
        if(cup2[v[nod][i]]==0 or cupleaza(v[nod][i])==1)
        {
            cup2[v[nod][i]]=nod;
            cup1[nod]=v[nod][i];
            return 1;

        }
    return 0;
}

int main()
{
    freopen("cuplaj.in","r",stdin);
    freopen("cuplaj.out","w",stdout);
    int n,m,e,sol=0,ok=1,x,y;
    scanf("%d%d%d",&n,&m,&e);
    for(int i=1;i<=e;i++)
    {
        scanf("%d%d",&x,&y);
        v[x].push_back(y);
    }
    while(ok>0)
    {
        ok=0;
        for(int i=1;i<=n;i++) vaz[i]=0;
        for(int i=1;i<=n;i++)
            if(cup1[i]==0) ok+=cupleaza(i);
    }
    for(int i=1;i<=n;i++)
        if(cup1[i]>0) sol++;
    printf("%d\n",sol);
    for(int i=1;i<=n;i++)
        if(cup1[i]>0) printf("%d %d\n",i,cup1[i]);
    return 0;
}