#include <fstream>
#include <vector>

using namespace std;

ifstream fin("cuplaj.in");
ofstream fout("cuplaj.out");

const int nmax= 10000, mmax= 10000;

vector <int> g[nmax+mmax+1];
int p[nmax+mmax+1];
bool up[nmax+1];

bool pair_up( int x ) {
    if ( up[x]==1 ) {
        return 0;
    }
    up[x]= 1;

    for ( vector <int>::iterator it= g[x].begin(); it!=g[x].end(); ++it ) {
        if ( p[*it]==0 ) {
            p[x]= *it; p[*it]= x;
            return 1;
        }
    }
    for ( vector <int>::iterator it= g[x].begin(); it!=g[x].end(); ++it ) {
        if ( pair_up(p[*it])==1 ) {
            p[x]= *it; p[*it]= x;
            return 1;
        }
    }

    return 0;
}

int main(  ) {
    int n, m, e;
    fin>>n>>m>>e;
    for ( int i= 1; i<=e; ++i ) {
        int x, y;
        fin>>x>>y;
        g[x].push_back(y+n);
        g[y+n].push_back(x);
    }

    int mm= 0, mods= 1;
    while ( mods>0 ) {
        mods= 0;
        for ( int i= 1; i<=n; ++i ) {
            up[i]= 0;
        }
        for ( int i= 1; i<=n; ++i ) {
            if ( p[i]==0 ) {
                mods+= pair_up(i);
            }
        }
        mm+= mods;
    }

    fout<<mm<<"\n";
    for ( int i= 1; i<=n; ++i ) {
        if ( p[i]!=0 ) {
            fout<<i<<" "<<p[i]-n<<"\n";
        }
    }

    return 0;
}