#include <bits/stdc++.h>

using namespace std;
ifstream fin("cuplaj.in");
ofstream fout("cuplaj.out");

vector <int> G[10005];
bitset <10005> uz;
int st[10005];
int dr[10005];
int cuplaj(int nod){
    int i,t;
    uz[nod] = 1;
    for(auto x : G[nod]){
        if(!dr[x]){
            st[nod] = x;
            dr[x] = nod;
            return 1;
        }
    }
    for(auto x : G[nod]){
        if(!uz[dr[x]] && cuplaj(dr[x])){
            st[nod] = x;
            dr[x] = nod;
            return 1;
        }
    }
    return 0;
}

int main()
{
    int n,i,j,m,e,u,v,ok,M = 0;
    fin >> n >> m >> e;
    for(i = 1; i <= e; i++){
        fin >> u >> v;
        G[u].push_back(v);
    }
    do{
        uz.reset();
        ok = 0;
        for(i = 1; i <= n; i++){
            if(!st[i] && cuplaj(i)) ok = 1;
        }
    }while(ok);
    for(i = 1; i <= n; i++){
        if(st[i]) M++;
    }
    fout << M << "\n";
    for(i = 1; i <= n; i++){
        if(st[i]) fout << i << " " << st[i] << "\n";
    }
    return 0;
}