#include<cstdio>
#include<vector>

using namespace std;

const int NMAX = 10000;

int n, m, e;
vector<int> adj[2][1 + NMAX];
int atr[2][1 + NMAX];
int vis[2][1 + NMAX];
int res[1 + NMAX];
int ct;

int connect(int nod)
{
    if(vis[0][nod] == 1)
    {
        return 0;
    }
    vis[0][nod] = 1;

    for(vector<int>::iterator it = adj[0][nod].begin(); it != adj[0][nod].end(); it++)
    {
        if(atr[1][*it] == 0)
        {
            atr[0][nod] = *it;
            atr[1][*it] = nod;
            return 1;
        }
    }
    for(vector<int>::iterator it = adj[0][nod].begin(); it != adj[0][nod].end(); it++)
    {
        if(connect(atr[1][*it]) == 1)
        {
            atr[0][nod] = *it;
            atr[1][*it] = nod;
            return 1;
        }
    }
    return 0;
}

void clear_vis()
{
    for(int i = 1; i <= n; i++)
    {
        vis[0][i] = 0;
    }
    for(int i = 1; i <= m; i++)
    {
        vis[1][i] = 0;
    }
}

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

    scanf("%d %d %d", &n, &m, &e);

    int x, y;
    for(int i = 1; i <= e; i++)
    {
        scanf("%d %d", &x, &y);
        adj[0][x].push_back(y);
        adj[1][y].push_back(x);
    }

    bool flag = 1;
    while(flag  == 1)
    {
        flag  = 0;
        ct = 0;
        for(int i = 1; i <= n; i++)
        {
            if(atr[0][i] == 0)
            {
                if(connect(i) == 1)
                {
                    flag = 1;
                }
            }
            else
            {
                ct++;
                res[ct] = i;
            }
        }

        clear_vis();
    }

    printf("%d\n", ct);
    for(int i = 1; i <= ct; i++)
    {
        printf("%d %d\n", res[i], atr[0][res[i]]);
    }
}