#include <iostream>
#include <vector>
#include <cstdio>
#include <queue>
#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef long double ld;

const int nax=(int)2e4+7;
int n,m,e;
vector <int> g[nax];
int match[nax];
int dist[nax];

void bfs()
{
        queue <int> q;
        for(int i=1;i<=n;i++)
                if(match[i]==0)
                {
                        q.push(i);
                        dist[i]=0;
                }
                else
                        dist[i]=-1;
        while(!q.empty())
        {
                int nod=q.front();
                for(auto nou : g[nod])
                {
                        nou=match[nou];
                        if(nou && dist[nou]==-1)
                        {
                                dist[nou]=1+dist[nod];
                                q.push(nou);
                        }
                }
                q.pop();
        }
        /// ma duc prin libere si ma intorc prin ocupate

}

bool vis[nax];

bool dfs(int nod)
{
     ///   cout<<nod<<"\n";
        vis[nod]=1;
        for(auto &nou : g[nod])
        {
                if(nou==0)
                {
                        cout<<"error : \n";
                        for(auto &x : g[1])
                                cout<<x<<" ";
                        cout<<"\n";
                        cout<<nod<<"\n";
                        exit(0);
                }
                if(match[nou]==0)
                {
                       /// cout<<" -> "<<nod<<" "<<nou<<"\n";
                        match[nod]=nou;
                        match[nou]=nod;
                        return 1;
                }
                if(dist[nod]+1==dist[match[nou]])
                        if(dfs(match[nou]))
                        {
                              ///  cout<<" -> "<<nod<<" "<<nou<<"\n";
                                match[nod]=nou;
                                match[nou]=nod;
                                return 1;
                        }
        }
        return 0;
}

int cuplaj()
{
        int ans=0;

        while(1)
        {
                bfs();
                int delta=0;
                for(int i=1;i<=n;i++)
                        vis[i]=0;
                for(int i=1;i<=n;i++)
                        delta+=(match[i]==0 && dfs(i));
                if(!delta)
                        break;
                ans+=delta;
        }

        return ans;
}

int main()
{
        freopen("cuplaj.in","r",stdin);
        freopen("cuplaj.out","w",stdout);

        cin>>n>>m>>e;
        while(e--)
        {
                int x,y;
                cin>>x>>y;
                y+=n;
                g[x].push_back(y);
                g[y].push_back(x);
        }

        cout<<cuplaj()<<"\n";
        for(int i=1;i<=n;i++)
                if(match[i])
                        cout<<i<<" "<<match[i]<<"\n";


        return 0;
}