#include <bits/stdc++.h>
using namespace std;
ifstream fin("cuplaj.in");
ofstream fout("cuplaj.out");
vector<int> v[10010];
vector<int> necupl;
int st[10010], dr[10010];
int n, m, k, x, y, muchie;
bitset<10010> viz;
bool creste(int nod)
{
if(viz[nod]) return 0;
viz[nod] = 1;
for(auto it:v[nod])
{
if(!st[it])
{
st[it] = nod;
dr[nod] = it;
return 1;
}
}
for(auto it:v[nod])
{
///dreapta a fost conectata
if(creste(st[it])) /// daca muchiile pot fi crescute
{
st[it] = nod;
dr[nod] = it;
return 1;
}
}
return 0;
}
bool oki_doki()
{
/// mergem pe toti membrii stg, daca un membru nu este conectat se apeleaza functia creste
bool ret = 0;
for(int i=1;i<=n;i++)
viz[i] = 0;
for(int i=1;i<=n; i++)
if(!dr[i] && creste(i)){
ret = 1;
muchie ++;
}
return ret;
}
int main()
{
fin >> n >> m;
fin >> k;
for(int i=1; i<=k; i++)
{
fin >> x >> y;
v[x].push_back(y);
}
///initializam conectiunea triviala
for(int i=1; i<=n; i++)
{
for(auto it:v[i])
{
if(st[it] == 0)
{
st[it] = i;
dr[i] = it;
muchie++;
break;
}
}
}
while(oki_doki());
fout<<muchie<<'\n';
for(int i=1; i<=n; i++)
if(dr[i]!=0)
fout<<i<<' '<<dr[i]<<'\n';
return 0;
}