#include <bits/stdc++.h>
using namespace std;
ifstream fin("cuplaj.in");
ofstream gout("cuplaj.out");

int nodes, edges, s, t, leftt, rightt;
vector<vector<pair<int, pair<int, int>>>> graphh;
vector<pair<int, int>> parrent;

void addedge(int x, int y){
    graphh[x].push_back({y, {1,graphh[y].size()}});
    graphh[y].push_back({x, {0,graphh[x].size()-1}});

}


void read(){
    fin>>leftt>>rightt>>edges;
    nodes=leftt+rightt;

    graphh.resize(nodes+3);
    parrent.resize(nodes+3);

    for(int i=0;i<edges;i++){
        int x,y;
        fin>>x>>y;
        addedge(x,y+leftt);

    }

    for(int i=1;i<=leftt;i++){
        addedge(0,i);
    }

    for(int i=leftt+1;i<=leftt+rightt;i++) {
        addedge(i,nodes+1);
    }
    s=0;
    t=nodes+1;

}

bool bfs(){
    vector <bool> viz(nodes+3);
    queue<int> q;
    q.push(s);
    viz[s]=true;
    parrent[s]={-1,-1};
    while(!q.empty()){
        int current_node = q.front();
        q.pop();
        int i=0;
        for(auto adj: graphh[current_node]){
            int c=adj.second.first;
            int adj_node=adj.first;
            if(!viz[adj_node] && c){
                parrent[adj_node]={current_node, i};
                if(adj_node==t){
                    return true;
                }
                viz[adj_node]=true;
                q.push(adj_node);
            }
            i++;
        }
    }
    return false;
}

int edmondsKarp(){
    long flux_max=0;
    while(bfs()){
        int x=t, path_min=1;
        while(parrent[x].first!=-1){
            int u=parrent[x].first;
            int v=parrent[x].second;
            path_min=min(path_min, graphh[u][v].second.first);
            x=parrent[x].first;
        }
        x=t;
        while(parrent[x].first!=-1){
            int u=parrent[x].first;
            int v=parrent[x].second;
            int w=graphh[u][v].second.second;
            graphh[u][v].second.first-=path_min;
            graphh[x][w].second.first+=path_min;
            x=parrent[x].first;
        }
        flux_max += path_min;

    }
    return flux_max;
}

int main(){
    read();
    gout << edmondsKarp() << '\n';
    for(int u = 1; u <= leftt; u++)
        for(auto node: graphh[u]){
            int v, c;
            v = node.first;
            c = node.second.first;
            if(v && c == 0 && v != t)
                gout << u << " " << v-leftt << '\n';
        }
    return 0;
}