#include <fstream>
#include <vector>

using namespace std;
ifstream in("cuplaj.in");
ofstream out("cuplaj.out");
const int N=10005;
int st[N],dr[N],n,m,k,sol;//side[x]=nodul care il are pe x in side(st/dr)
vector<int>a[N];
bool viz[N];
void resetviz();

bool cupleaza(int x)
{
    if(viz[x]==true)
        return false;
    viz[x]=true;
    int y;
    for(unsigned i=0;i<a[x].size();i++)
    {
        y=a[x][i];
        if(dr[y]==0)//cuplez cu un vecin nefolosit
        {
            dr[y]=x;
            st[x]=y;
            sol++;//cresc cardinalitatea, adaug o muchie
            return true;
        }
    }
    for(unsigned i=0;i<a[x].size();i++)
    {
        y=a[x][i];
        if(cupleaza(dr[y]))//pot schimba fostul nod conectat la y, pentru a cupla x la y
        {
            dr[y]=x;
            st[x]=y;
            return true;//nu mai cresc solutia, nr de muchii alese ramane acelasi, doar schimb capetele
        }
    }
    return false;
}

int main()
{
    in>>n>>m>>k;
    for(int x,y,i=1;i<=k;i++)
    {
        in>>x>>y;
        a[x].push_back(y);
    }
    bool ok=true;
    while(ok)
    {
        ok=false;
        resetviz();
        for(int i=1;i<=n;i++)
            if(st[i]==0 && cupleaza(i))//st[i]=0-->necuplat si cupleaza-->reusesc sa cuplez
                ok=true;//fac o schimbare,continua ciclul
    }//cuplare bubble
    out<<sol<<'\n';
    for(int i=1;i<=n;i++)
        if(st[i]!=0)
            out<<i<<' '<<st[i]<<'\n';
    return 0;
}
void resetviz()
{
    for(int i=1;i<=n;i++)
        viz[i]=false;
}