#include <stdio.h>
#include <vector>
#include <string.h>
#define NMAX 10010
using namespace std;

vector<int> G[NMAX];
bool done, viz[NMAX];
int L[NMAX], R[NMAX], N, M, E, i, a, b, cuplaj;


bool pairup(int n) {
    if (viz[n]) {
        return false;
    }
    viz[n] = true;
    
    for (vector<int>::iterator it = G[n].begin(); it != G[n].end(); it++) {
        if (!R[*it] || pairup(R[*it])) {
            L[n] = *it;
            R[*it] = n;
            return true;
        }
    }
    
    return false;
}


int main(int argc, char **argv)
{
    freopen("cuplaj.in", "r", stdin);
    freopen("cuplaj.out", "w", stdout);
    
    scanf("%d %d %d", &N, &M, &E);
    for (i = 1; i <= E; i++) {
        scanf("%d %d", &a, &b);
        G[a].push_back(b);
    }
    
    while (!done) {
        done = true;
        memset(viz, false, sizeof(viz));
        
        for (i = 1; i <= N; i++) {
            if (!L[i] && pairup(i)) {
                cuplaj++;
                done = false;
            }
        }
    }
    
    printf("%d\n", cuplaj);
    for (i = 1; i <= N; i++) {
        if (L[i]) {
            printf("%d %d\n", i, L[i]);
        }
    }
    
    return 0;
}