#include <bits/stdc++.h>

#define NMax 10005
using namespace std;
ifstream f("cuplaj.in");
ofstream g("cuplaj.out");

int n,m,l,x,ANS,y;
int vR[NMax],vL[NMax];
bool viz[NMax];
vector<int> G[NMax];

int cuplaj(int nod){
    if(viz[nod])
        return 0;
    viz[nod] = 1;
    for(int i = 0; i < G[nod].size(); ++i){
        if(!vL[G[nod][i]]){
            vL[G[nod][i]] = nod;
            vR[nod] = G[nod][i];
            return 1;
        }
    }
    for(int i = 0; i < G[nod].size(); ++i){
        if(cuplaj(vL[G[nod][i]])){
            vL[G[nod][i]] = nod;
            vR[nod] = G[nod][i];
            return 1;
        }
    }
    return 0;
}
int main()
{
    f >> n >> m >> l;
    for(int i = 1; i <= l; ++i){
        f >> x >> y;
        G[x].push_back(y);
    }
    int ok = 1;
    while(ok){
        ok = 0;
        memset(viz,0,sizeof(viz));
        for(int i = 1; i <= n; ++i){
            if(!vR[i]){
                if(cuplaj(i)){
                    ok = 1;
                    ANS++;
                }
            }
        }
    }
    g << ANS << '\n';
    for(int i = 1; i <= n; ++i){
        if(vR[i]){
            g << i << ' ' << vR[i] << '\n';
        }
    }
    return 0;
}