#include<cstdio>
#include<vector>
#include<cstring>
using namespace std;
#define N 10001
#define F(i,V) for(vector<int>::iterator i=V.begin();i!=V.end();i++)
vector<int> g[N];
int l[N],r[N],u[N],n,m,e,x,y,c=1,i,j;
int P(int n)
{
if(u[n])
return 0;
u[n]=1;
F(i,g[n])
if(!r[*i])
{
l[n]=*i,r[*i]=n;
return 1;
}
F(i,g[n])
if(P(r[*i]))
{
l[n]=*i,r[*i]=n;
return 1;
}
return 0;
}
int main()
{
freopen("cuplaj.in","r",stdin),freopen("cuplaj.out","w",stdout),scanf("%d%d%d",&n,&m,&e);
while(e--)
scanf("%d%d",&x,&y),g[x].push_back(y);
while(c)
for(c=0,memset(u,0,sizeof(u)),i=1;i<=n;i++)
if(!l[i])
c|=P(i);
for(i=1;i<=n;i++)
j+=(l[i]>0);
printf("%d\n",j);
for(i=1;i<=n;i++)
if(l[i]>0)
printf("%d %d\n",i,l[i]);
}