#include <cstdio>
#include <cstring>
#include <vector>
#define nmax 10001
using namespace std;
 
int n,m,e,nr;
vector <int> graf[nmax];
int dr[nmax];
int st[nmax];
int viz[nmax];
 
void read()
{
 
    int x,y;
    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);
        graf[x].push_back(y);
    }
}
 
int HopcroftKarp(int nod)
{
 
   if(viz[nod]) return 0;
   viz[nod] = 1;
   for (int i=0;i<=graf[nod].size();++i)
           if(!dr[i] || HopcroftKarp(dr[i])){
            st[nod]=i;
            dr[i]=nod;
            return 1;
        }
return 0;
}

void solve()
{
 
    int ok=1;
    while(ok)
	{
        ok = 0;
    for(int i=1;i<=n;++i)
        if(!st[i])
        if(HopcroftKarp(i)) {ok=1;++nr;}
 
            memset(viz,0,sizeof(viz));
 
}
   
}

void write()
{
	 printf("%d\n",nr);
    for(int i=1;i<=n;++i)
        if(st[i])
            printf("%d %d\n",i,st[i]);
}
 
int main(){
 
    read();
    solve();
	write();
 
return 0;
}