#include<bits/stdc++.h>
using namespace std;
ifstream f("cuplaj.in");ofstream g("cuplaj.out");
const int N = 10010;
void read(),solve();
int n,m,e,C,S[N],D[N],creste(int),OK();
bitset<N> viz;
vector<int> v[10010];
int main()
{
    int x,y;f>>n>>m>>e;
    for(;e;e--){f>>x>>y;v[x].push_back(y);}
    for(;OK(););g<<C<<'\n';for(int i=1;i<=n;i++) if(D[i])g<<i<<' '<<D[i]<<'\n';

    return 0;
}

int OK()
{
    int ret=0;viz.reset();for(int i=1;i<=n;i++) if(!D[i]&&creste(i)){C++;ret=1;} return ret;
}
int creste(int s)
{
    if(viz[s])return 0;viz[s]=1;
    for(auto d:v[s]) if(!S[d])       {D[s]=d;S[d]=s;return 1;}
    for(auto d:v[s]) if(creste(S[d])){D[s]=d;S[d]=s;return 1;}
    return 0;
}