#include <iostream>
#include <cstdio>
#include <vector>
using namespace std;
vector<vector<int> > Graph(10001);
int N, M, E, i, j, ToLeft[10001], ToRight[10001], done, Sol;
bool Check[10001];
int Parc(int i);
int main()
{
    freopen("cuplaj.in", "r", stdin);
    freopen("cuplaj.out", "w", stdout);
    scanf("%d%d%d", &N, &M, &E);
    for(i=1; i<=N; ++i) Graph[i].push_back(0);
    for(i=1; i<=E; ++i){
        int x, y;
        scanf("%d%d", &x, &y);
        ++Graph[x][0];
        Graph[x].push_back(y);
    }
    do{
        done=0;
        for(i=1; i<=N; ++i) Check[i]=false;
        for(i=1; i<=N; ++i) if(ToRight[i]==0) if(Parc(i)==1) {++Sol; done=1;}
    } while(done!=0);
    printf("%d\n", Sol);
    for(i=1; i<=N; ++i) if(ToRight[i]!=0) printf("%d %d\n", i, ToRight[i]);
    return 0;
}
int Parc(int i){
    int j;
    if(Check[i]==true) return 0;
    Check[i]=true;
    for(j=1; j<=Graph[i][0]; ++j) if(ToLeft[Graph[i][j]]==0){
        ToRight[i]=Graph[i][j];
        ToLeft[Graph[i][j]]=i;
        return 1;
    }
    for(j=1; j<=Graph[i][0]; ++j) if(Parc(ToLeft[Graph[i][j]])==1){
        ToRight[i]=Graph[i][j];
        ToLeft[Graph[i][j]]=i;
        return 1;
    }
    return 0;
}