#include <fstream>
#include <vector>
#include <cstring>
#define nmax 10001
using namespace std;
ifstream is ("cuplaj.in");
ofstream os ("cuplaj.out");

vector <int> V[nmax];
int N, M, E, ANSW;
int U[nmax], L[nmax], R[nmax];
void Read();
int Solve(int x);

int main()
{
    Read();
    bool ok = true;
    while(ok) {
        ok = false;
        memset(U, 0, sizeof(U));
        for(int i = 1; i <= N; ++i)
            if(!L[i]) ok |= Solve(i);
    }

    for(int i = 1; i <= N; ++i)
        if(L[i] > 0) ANSW ++;

    os << ANSW << "\n";
    for(int i = 1; i <= N; ++i)
        if(L[i]) os << i << " " << L[i] << "\n";

    is.close();
    os.close();
    return 0;
}
void Read()
{
    int x, y;
    is >> N >> M >> E;
    for(int i = 1; i <= E; ++i)
    {
        is >> x >> y;
        V[x].push_back(y);
    }
}
int Solve(int x)
{
    if(U[x]) return 0;
    U[x] = 1;
    for(const auto& i : V[x])
    {
        if(!R[i])
        {
            L[x] = i;
            R[i] = x;
            return 1;
        }
        if(Solve(R[i]))
        {
            L[x] = i;
            R[i] = x;
            return 1;
        }
    }
    return 0;
}