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

#define N 10010
#define INF 100010
int n,m;

vector<int> adj[N];
int pairU[N], pairV[N], dist[N];
int ans;


bool bfs(){

    queue<int> q;
    for(int i = 1;i<=n;i++){
        if(pairV[i] == 0){
            q.push(i);
            dist[i] = 0;
        }
        else dist[i] = INF;
    }
    dist[0] = INF;
    while(!q.empty()){
        int u = q.front();
        q.pop();

        if(dist[u] < dist[0]){
            for(auto v: adj[u]){
                if(dist[pairU[v]] == INF){

                    dist[pairU[v]] = dist[u] + 1;
                    q.push(pairU[v]);
                }
            }
        }
    }

    return dist[0] != INF;

}

bool dfs(int u){
    if(u == 0)
        return true;
    for(auto v: adj[u]){
        if(dist[pairU[v]] == dist[u] + 1){
            if(dfs(pairU[v])){
                pairU[v] = u;
                pairV[u] = v;
                return true;
            }
        }
    }
    dist[u] = INF;
    return false;
}

void cuplaj(){

    while(bfs()){
        for(int i = 1;i<=n;i++){
            if(pairV[i] == 0){
                if(dfs(i)){
                    ans++;
                }
            }
        }
    }
}

int main(){

    ifstream cin("cuplaj.in");
    ofstream cout("cuplaj.out");

    int e;
    cin>>n>>m>>e;

    for(int i = 0; i<e;i++){
        int a, b;
        cin>>a>>b;
        adj[a].push_back(b);
    }

    cuplaj();
    cout<<ans<<'\n';

    for(int i = 1;i<=n;i++){
        if(pairV[i])
            cout<<i<<' '<<pairV[i]<<'\n';
    }

    return 0;
}