#include <iostream>
#include <fstream>
#include <cstring>
#include <vector>
using namespace std;
ifstream f("cuplaj.in");
ofstream g("cuplaj.out");
vector<int> graf[10001];
int cupl1[10001],cupl2[10001];
int folosit[1001],n,m,e,schimba;
int cupleaza(int x)
{
    if(folosit[x]) return 0;
    folosit[x]=1;
    for(vector<int>::iterator it=graf[x].begin();it!=graf[x].end();it++)
        if(cupl2[*it]==0)
    {
        cupl1[x]=*it;
        cupl2[*it]=x;
        return 1;
    }
    for(vector<int>::iterator it=graf[x].begin();it!=graf[x].end();it++)
        if(cupleaza(cupl2[*it]))
    {
        cupl1[x]=*it;
        cupl2[*it]=x;
        return 1;
    }
    return 0;
}
int main()
{
    f>>n>>m>>e;
    for(int i=1;i<=e;i++)
    {
        int x1,x2;
        f>>x1>>x2;
        graf[x1].push_back(x2);
    }
    schimba=1;
    while(schimba)
    {
        schimba=0;
        for(int i=1;i<=n;i++)
            folosit[i]=0;
        for(int i=1;i<=n;i++)
            if(!cupl1[i]) schimba+=cupleaza(i);
    }
    int nr=0;
    for(int i=1;i<=n;i++)
        if(cupl1[i]) nr++;
    g<<nr<<"\n";
    for(int i=1;i<=n;i++)
        if(cupl1[i]) g<<i<<" "<<cupl1[i]<<"\n";
    return 0;
}