#include <cstdio>
#include <cstdlib>
#include <vector>
#include <algorithm>
using namespace std;

#define Nmax 100010
#define pb push_back
#define forit(it, v) for(typeof((v).begin()) it = (v).begin(); it != (v).end(); ++ it)

int L[Nmax], R[Nmax], N, M, E, X, Y;
bool Used[Nmax];
vector<int> G[Nmax];

int PairUp(int Node)
{
    if(Used[Node]) return 0;
    Used[Node] = 1;
    forit(it, G[Node])
        if(!R[*it] || PairUp(R[*it]))
        {
            L[Node] = *it;
            R[*it] = Node;
            return 1;
        }
    return 0;
}

int MaxMatching()
{
    int Ans = 0, OK = 1;
    while(OK)
    {
        OK = 0;
        for(int i = 1; i <= N; ++ i) Used[i] = 0;
        for(int i = 1; i <= N; ++ i)
            if(!L[i] && PairUp(i))
                Ans ++, OK = 1;
    }
    return Ans;
}

int main()
{
    freopen("cuplaj.in", "r", stdin);
    freopen("cuplaj.out", "w", stdout);
    int i, j;
    scanf("%i %i %i", &N, &M, &E);
    for(i = 1; i <= E; ++ i)
    {
        scanf("%i %i", &X, &Y);
        G[X].pb(Y);
    }
    printf("%i\n", MaxMatching());
    for(i = 1; i <= N; ++ i)
        if(L[i])
            printf("%i %i\n", i, L[i]);
    return 0;
}