#include<bits/stdc++.h>
#define maxN 10005
using namespace std;
bool seen[maxN];
int l[maxN],r[maxN],x,y,augment,n,m,e;
vector<int> v[maxN];
inline int path(int nod)
{
    if(seen[nod]) return 0;
    seen[nod]=1;
    for(vector<int>::iterator it=v[nod].begin();it!=v[nod].end();it++)
    {
        if(!r[*it])
        {
            l[nod]=*it;
            r[*it]=nod;
            return 1;
        }
    }
    for(vector<int>::iterator it=v[nod].begin();it!=v[nod].end();it++)
    {
        if(path(r[*it]))
        {
            l[nod]=*it;
            r[*it]=nod;
            return 1;
        }
    }
    return 0;
}
int main()
{
    freopen("cuplaj.in","r",stdin);
    freopen("cuplaj.out","w",stdout);
    scanf("%d%d%d",&n,&m,&e);
    for(int i=1;i<=e;i++)
    {
        scanf("%d%d",&x,&y);
        v[x].push_back(y);
    }
    augment=1;
    while(augment)
    {
        augment=0;
        memset(seen,0,sizeof(seen));
        for(int i=1;i<=n;i++)
        {
            if(!l[i])
            {
                augment=augment|path(i);
            }
        }
    }
    int cuplaj=0;
    for(int i=1;i<=n;i++)
    {
        if(l[i]) cuplaj++;
    }
    printf("%d\n",cuplaj);
    for(int i=1;i<=n;i++)
    {
        if(l[i]) printf("%d %d\n",i,l[i]);
    }
    return 0;
}