#include <bits/stdc++.h>
#define NMAX 10002

using namespace std;

ifstream fin("cuplaj.in");
ofstream fout("cuplaj.out");

int N,M,E;
vector <int> G[NMAX];
int L[NMAX],R[NMAX];
char used[NMAX];

bool pairup(int node)
{
    if(used[node]) return false;
    used[node] = 1;
    for(int x : G[node]){
        if(R[x] == 0){///cautam vecin ne imperecheat
            L[node] = x;
            R[x] = node;
            return true;
        }
    }
    for(int x : G[node]){
        if(pairup(R[x])){///incercam sa imperechem cu unu deja imperecheat
            L[node] = x;
            R[x] = node;
            return true;
        }
    }
    return false;
}

int main()
{
    fin >> N >> M >> E;
    for(int i=1;i<=E;i++){
        int x,y;
        fin >> x >> y;
        G[x].push_back(y);
    }
    bool ok = true;
    while(ok){
        ok = false;
        memset(used, 0, sizeof(used));
        for(int i=1;i<=N;i++){
            if(L[i] == 0){
                if(pairup(i)){///tot imperechem pana nu se mai schimba nimica
                    ok = true;
                }
            }
        }
    }
    vector <pair<int,int>> ans;
    for(int i=1;i<=N;i++){
        if(L[i] != 0){
            ans.push_back({i, L[i]});
        }
    }
    fout << ans.size() << "\n";
    for(auto [x,y] : ans){
        fout << x << " " << y << "\n";
    }
    return 0;
}