#include<fstream>
#include<cstring>
#include<vector>
#define MAXN 10001
using namespace std;
int l[MAXN],r[MAXN],viz[MAXN],n,m,nrm,sol;
vector<int> g[MAXN];
ifstream fin("cuplaj.in");
ofstream fout("cuplaj.out");
void citire()
{
    int x,y;
    fin>>n>>m>>nrm;
    for(int i=1;i<=nrm;i++)
    {
        fin>>x>>y;
        g[x].push_back(y);
    }
}

int cupleaza(int nod)
{
    viz[nod]=1;
    for(int i=0;i<g[nod].size();i++)
    {
        if(!r[g[nod][i]])
        {
            l[nod]=g[nod][i];
            r[g[nod][i]]=nod;
            return 1;
        }
    }
    for(int i=0;i<g[nod].size();i++)
    {
        if(viz[r[g[nod][i]]]==0 && cupleaza(r[g[nod][i]]))
        {
            //verific daca pot cupla perechea lui g[nod][i] cu altceva ca sa cuplez nod cu g[nod][i]
            l[nod]=g[nod][i];
            r[g[nod][i]]=nod;
            return 1;
        }
    }
    return 0;
}

int main()
{
    citire();
    int ok;
    do
    {
        ok=0;
        memset(viz,0,sizeof(viz));
        for(int i=1;i<=n;i++)
        {
            if(!l[i] && viz[i]==0 && cupleaza(i))
            {
                ok=1;
                sol++;
            }

        }
    }while(ok);
    fout<<sol<<"\n";
    for(int i=1;i<=n;i++)
    {
        if(l[i])
        {
            fout<<i<<" "<<l[i]<<"\n";
        }

    }
    return 0;
}