#include <iostream>
#include <bits/stdc++.h>
using namespace std;

//ifstream in("maxflow.in");
//ofstream out("maxflow.out");
ifstream in("cuplaj.in");
ofstream out("cuplaj.out");


vector<int> adjList[10005];
vector<int> u(10005);
int l[10005], r[10005];

int pairup(int n){
    if (u[n])
        return 0;
    u[n] = 1;
    for(auto el : adjList[n]){
        if(!r[el])
        {
            l[n] = el;
            r[el] = n;
            return 1;
        }
    }
    for(auto el: adjList[n]){
        if(pairup(r[el])){
            l[n] = el;
            r[el] = n;
            return 1;
        }
    }
    return 0;
}
int main(){
    int n,m,e;
    in>>n>>m>>e;

    for(int i = 0; i<e; i++)
    {
        int x,y;
        in>>x>>y;
        adjList[x].push_back(y);
    }
    int unpair = 1;
    while(unpair) {
        unpair = 0;
        fill(u.begin(), u.end(), 0);
        for(int j =1; j<=n;j++)
            if(!l[j])
                unpair += pairup(j);

    }

    int mxFlow = 0;
    for(int i = 1; i<=n ;i++)
        mxFlow += (l[i] > 0);
    out<<mxFlow<<endl;
    for(int i=1 ; i<=n; i++)
        if(l[i] > 0)
            out<<i<<" "<<l[i]<<endl;
    return 0;
}