#include <iostream>
#include <vector>
#include <fstream>
#include <queue>
#define max_capacity INT_MAX

using namespace std;
ifstream fin("cuplaj.in");
ofstream fout("cuplaj.out");
int n, m, e, max_flow;
int capacity[20002][20002];
vector<int>parent, visited;
vector<int>adjacency_list[20002];
queue<int>q;

int bfs(){
    visited.assign(n+m+2, 0);
    parent.assign(n+m+2, 0);
    while(!q.empty()){
        q.pop();
    }
    q.push(0);
    visited[0]=1;
    parent[0]=0;
    while(!q.empty()){
        int node=q.front();
        q.pop();
        for(auto neighbour:adjacency_list[node]){
            if(visited[neighbour]==0 && capacity[node][neighbour]>0) {
                q.push(neighbour);
                parent[neighbour]=node;
                visited[neighbour]=1;
                if(neighbour == n+m+1) return 1;
            }
        }
    }
    return visited[n+m+1];
}

int main() {
    fin>>n>>m>>e;
    int x, y;
    for(int i=0; i<e; i++){
        fin>>x>>y;
        y += n;
        adjacency_list[x].push_back(y);
        adjacency_list[y].push_back(x);
        adjacency_list[0].push_back(x);
        adjacency_list[x].push_back(0);
        adjacency_list[y].push_back(n+m+1);
        adjacency_list[n+m+1].push_back(y);
        capacity[x][y]=1;
        capacity[0][x]=1;
        capacity[y][n+m+1]=1;
    }
    while(bfs()) {
        for (auto node: adjacency_list[n+m+1]) {
            if (!visited[node])
                continue;
            parent[n+m+1] = node;
            int flow = max_capacity;
            for (node = n+m+1; node != 0; node = parent[node]) {
                flow = min(flow, capacity[parent[node]][node]);
            }
            if (flow == 0) continue;
            for (node = n+m+1; node != 0; node = parent[node]) {
                capacity[parent[node]][node] -= flow;
                capacity[node][parent[node]] += flow;
            }
            max_flow += flow;
        }
    }
    fout<<max_flow<<'\n';
    for(int i=1; i<=n; i++){
        for(int j=n+1; j<=m+n+1; j++){
            if(capacity[i][j] == 0 && capacity[j][i] == 1){
                fout<<i<<" "<<j-n<<'\n';
            }
        }
    }
    fin.close();
    fout.close();
    return 0;
}