#include<cstdio>
#include<vector>
#include<bitset>
using namespace std;
const int nmax = 10005;
int i,n,m,e,x,y,ok,sol,l[nmax],r[nmax];
vector<int> v[nmax];
bitset<nmax> viz;
bool pairup(int x)
{
    if(viz[x]) return 0; viz[x]=1;
    for(vector<int>::iterator it=v[x].begin();it!=v[x].end();it++)
        if(!r[*it] || pairup(r[*it]))
        {
            l[x]=*it; r[*it]=x;
            return 1;
        }
    return 0;
}
int main()
{
	freopen("cuplaj.in","r",stdin);
	freopen("cuplaj.out","w",stdout);
	scanf("%d%d%d",&n,&m,&e);
	for(;e;e--)
	{
	    scanf("%d%d",&x,&y);
	    v[x].push_back(y);
	}
	for(ok=1;ok;)
	{
	    ok=0; viz=0;
	    for(i=1;i<=n;i++)
            if(!l[i] && pairup(i)) ok=1,sol++;
	}
	printf("%d\n",sol);
	for(i=1;i<=n;i++) if(l[i]) printf("%d %d\n",i,l[i]);
	return 0;
}