#include <bits/stdc++.h>

using namespace std;

#define FILE_IO

int N, M, K, ans;
vector <int> edg[10005];
int f[10005], l[10005], r[10005];

bool match(int nod)
{
    if(f[nod])  return 0;
    f[nod] = 1;

    for(auto nxt: edg[nod])
        if( !r[nxt] )
        {
            l[nod] = nxt;
            r[nxt] = nod;
            return 1;
        }

    for(auto nxt: edg[nod])
        if( match(r[nxt]) )
        {
            l[nod] = nxt;
            r[nxt] = nod;
            return 1;
        }
    return 0;
}

int main()
{
    #ifdef FILE_IO
    freopen("cuplaj.in", "r", stdin);
    freopen("cuplaj.out", "w", stdout);
    #endif

    scanf("%d%d%d", &N, &M, &K);
    for(int i = 1; i <= K; i++)
    {
        int x, y;
        scanf("%d%d", &x, &y);
        edg[x].push_back(y);
    }

    int ok = 1;
    while(ok)
    {
        ok = 0;
        memset(f, 0, sizeof(f));
        for(int i = 1; i <= N; i++)
            if( !l[i] )
                if( match(i) )
                    ok = 1;
    }

    for(int i = 1; i <= N; i++)
        if(l[i])    ans++;
    printf("%d\n", ans);
    for(int i = 1; i <= N; i++)
        if(l[i])
            printf("%d %d\n", i, l[i]);

    return 0;
}