#include <bits/stdc++.h>
using namespace std;

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

typedef long long I64;

struct Cuplaj
{
    static const int NMAX = 10000;

    int cuplate;
    vector<int> G[NMAX+2];
    bool viz[NMAX+2];
    int st[NMAX+2], dr[NMAX+2];
    int N, M, E;

    Cuplaj(int n, int m)
    {
        cuplate = 0;
        N = n, M = m;
        memset(st, 0, sizeof(st));
        memset(dr, 0, sizeof(dr));
    }

    addEdge(int x, int y)
    {
        G[x].push_back(y);
    }



    bool cuplaj(int nod)
    {
        viz[nod] = 1;

        for( auto x : G[nod] ) {
            if( !dr[x] ) {
                dr[x] = nod;
                st[nod] = x;
                ++cuplate;
                return 1;
            }
        }
        for( auto x : G[ nod ] ) {
            if( !viz[ dr[x] ] && cuplaj(dr[x]) ) {
                st[nod] = x;
                dr[x] = nod;
                return 1;

            }
        }
        return 0;
    }

    vector<pair<int,int>> make_cuplaj()
    {
        vector<pair<int,int>> sol;

        bool ok = 0;
        while( !ok ) {
            ok = 1;
            memset(viz, 0, sizeof(viz));

            for( int i = 1;  i <= N;  ++i ) {
                if( !st[i] && cuplaj(i) )
                    ok = 0;
            }
        }

        for( int i = 1;  i <= N;  ++i ) if( st[i] )
            sol.push_back({i, st[i]});
        return sol;
    }
};

int N, M, E;

int main()
{
    in >> N >> M >> E;
    Cuplaj problema(N, M);
    for( int i = 1;  i <= E;  ++i ) {
        int x,y;
        in >> x >> y;
        problema.addEdge(x, y);
    }

    auto sol = problema.make_cuplaj();
    out << sol.size() << '\n';
    for( auto p : sol ) out << p.first << ' ' << p.second << '\n';

    return 0;
}