#include<fstream>
#include<cstring>
#include<vector>
#include<queue>
using namespace std ;

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

#define maxn 10005

int N, M, E ;
vector< vector<int> > graf ;

int solution;

int cuplaj[ 2 * maxn + 1 ], tata[ 2 * maxn + 1 ] ;

int bfs(int nod)
{
    queue<int> coada ;
    coada.push(nod) ;

    tata[nod] = -1 ;

    while( coada.empty() == false )
    {
        int act = coada.front() ;
        coada.pop() ;

        if( act <= N )
        {
            for(size_t i = 0; i < graf[act].size(); ++i )
            {
                int vecin = graf[act][i] ;

                if( tata[vecin] == 0 )
                {
                    tata[vecin] = act ;
                    if( cuplaj[vecin] == 0 )
                        return vecin ;
                    coada.push( vecin ) ;
                }
            }
        }
        else
        {
            tata[ cuplaj[act] ] = act ;
            coada.push( cuplaj[act] ) ;
        }
    }

    return 0 ;
}

void cupleaza(int nod)
{
    bool ok = true ;

    while( tata[nod] > 0 )
    {
        if( ok == true )
        {
            cuplaj[nod] = tata[nod] ;
            cuplaj[ tata[nod] ] = nod ;
        }

        ok = !ok ;
        nod = tata[nod] ;
    }
}

int main()
{
    fin >> N >> M >> E ;
    graf.resize( N + M + 1 ) ;

    for(int i = 0; i < E; ++i )
    {
        int x, y ;
        fin >> x >> y ;
        graf[x].push_back( y + N ) ;
        graf[ y + N ].push_back(x) ;
    }

    int nr = 0 ;

    for(int i = 1; i <= N; ++i )
    {
        for(size_t j = 0; j < graf[i].size(); ++i )
        {
            int vecin = graf[i][j] ;

            if( cuplaj[vecin] == 0 )
            {
                cuplaj[i] = vecin ;
                cuplaj[vecin] = i ;
                ++nr ;
                break ;
            }
        }
    }

    while( 1 )
    {
        bool ok = false ;
        memset( tata, 0, sizeof(tata) ) ;

        for(int i = 1; i <= N; ++i )
        {
            if( cuplaj[i] == 0 )
            {
                int act = bfs(i) ;

                if( act )
                {
                    ok = true ;
                    cupleaza(act) ;
                    ++nr ;
                }
            }
        }

        if( ok == false )
            break ;
    }

    fout << nr << "\n" ;

    for(int i = 1; i <= N; ++i )
        if( cuplaj[i] )
            fout << i << " " << cuplaj[i] - N << "\n" ;

    return 0 ;
}