# include <iostream>
# include <fstream>
# include <vector>
# include <cstring>

using namespace std;

const int MAX_N = 10000;
vector<int> bords[1 + MAX_N];

int l[1 + MAX_N];
int r[1 + MAX_N];
bool f[1 + MAX_N];

bool match( int u ) {
    if ( f[u] )
        return false;
    f[u] = true;

    for ( int v : bords[u] )
        if ( !r[v] ) {
            l[u] = v;
            r[v] = u;
            f[u] = false;
            return true;
        }

    for ( int v : bords[u] )
        if ( !f[r[v]] && match( r[v] ) ) {
            l[u] = v;
            r[v] = u;
            f[u] = false;
            return true;
        }

    return false;
}

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

    int n, m, e;
    fin >> n >> m >> e;

    for ( int i = 0; i < e; i ++ ) {
        int a, b;
        fin >> a >> b;
        bords[a].push_back( b );
    }

    int cuplaj = 0;
    bool matched_any;
    do {
        matched_any = false;
        for ( int i = 1; i <= n; i ++ ) {
            if ( !l[i] && match( i ) ) {
                cuplaj ++;
                matched_any = true;
            }
        }
    } while ( matched_any );

    fout << cuplaj << '\n';
    for ( int i = 1; i <= n; i ++ )
        if ( l[i] )
            fout << i << ' ' << l[i] << '\n';

    return 0;
}