#include <cstdio>
#include <algorithm>

using namespace std;

vector <int> v[10005];
bool used[10005];
int L[10005], R[10005];

bool match(int node){
    if(used[node]){
        return 0;
    }
    used[node] = 1;
    for(auto it : v[node]){
        if(R[it] == 0){
            L[node] = it;
            R[it] = node;
            return 1;
        }
    }
    for(auto it : v[node]){
        if(match(R[it])){
            L[node] = it;
            R[it] = node;
            return 1;
        }
    }
    return 0;
}

int main(){
    int n,m,e,i,j,x,y;
    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", &x, &y);
        v[x].push_back(y);
    }
    int ans = 0;
    bool ok;
    for(ok = 1;ok;){
        ok = 0;
        for(i = 1;i <= n;i++){
            used[i] = 0;
        }
        for(i = 1;i <= n;i++){
            if(L[i] == 0){
                if(match(i)){
                    ok = 1;
                    ans++;
                }
            }
        }
    }
    printf("%d\n", ans);
    for(i = 1;i <= n;i++){
        if(L[i]){
            printf("%d %d\n", i, L[i]);
        }
    }
    return 0;
}