//#include <iostream>
#include <fstream>
#include <vector>
using namespace std;

vector<int> v[10005];
int mom[10005];
int per[10005];
bool viz[10005];
int cup[10005];
ifstream cin("cuplaj.in");
ofstream cout("cuplaj.out");
bool rec(int nod){
    if(viz[nod]==1){
        return 0;
    }
    viz[nod]=1;
    for(int i=0;i<v[nod].size();i++){
        if(per[v[nod][i]]==-1){
            per[v[nod][i]]=nod;
            cup[nod]=v[nod][i];
            return 1;
        }
        else{
            if(viz[v[nod][i]]==0 and rec(per[v[nod][i]])==1){
                per[v[nod][i]]=nod;
                cup[nod]=v[nod][i];
                return 1;
            }
        }
    }
    return 0;
}
int main()
{
    int n,m,e,a,b;
    cin>>n>>m>>e;
    for(int i=1;i<=e;i++){
        cin>>a>>b;
        v[a].push_back(b);
    }
    for(int i=1;i<=m;i++){
        per[i]=-1;
    }
    int prevcnt=0,cnt=0;
    do{
        prevcnt=cnt;
        cnt=prevcnt;
        for(int j=1;j<=n;j++){
            viz[j]=0;
        }
        for(int i=1;i<=n;i++){
            if(cup[i]==0)
                cnt+=rec(i);
        }

    }while(prevcnt!=cnt);
    cout<<cnt<<"\n";
    for(int i=1;i<=m;i++){
        if(per[i]!=-1){
            cout<<per[i]<<" "<<i<<"\n";
        }
    }
    return 0;
}