#include <bits/stdc++.h>

using namespace std;

#define FILE_IO

typedef pair<int, int> pii;

class MaximumMatchings
{
public:
    int N = 0;
    vector <pii> edges;
    vector <int> edg[20005];
    int mtc[20005];
    int t, tr[20005];

    MaximumMatchings()
    {
        N = 0;
        edges.clear();
        t = 0;
        memset(tr, 0, sizeof(tr));
        memset(mtc, 0, sizeof(mtc));
    }

    void addEdge(int x, int y)
    {
        edges.push_back({x, y});
        edg[x].push_back(y);
        edg[y].push_back(x);
        N = max(N, max(x, y));
    }

    void matchNodes(int x, int y) { mtc[x] = y; mtc[y] = x; }

    bool match(int nod)
    {
        if(tr[nod] == t)    return false;
        tr[nod] = t;

        for(auto nxt: edg[nod])
            if( mtc[nxt] == 0 || match(mtc[nxt]) ) { matchNodes(nod, nxt); return true; }

        return false;
    }

    vector<pii> getMaximumMatchings()
    {
        vector<pii> ans;
        bool newMatching = true;
        t = 0;
        while( newMatching )
        {
            t++;
            newMatching = false;
            for(int i = 1; i <= N; i++)
                if(!mtc[i])
                    if( match(i) )
                        newMatching = true;
        }

        for(int i = 1; i <= N; i++)
            if(mtc[i] && mtc[i] > i)
                ans.push_back({i, mtc[i]});
        return ans;
    }
};

MaximumMatchings m;

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

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

    auto ans = m.getMaximumMatchings();
    printf("%d\n", ans.size());
    for(auto mtc: ans)
    {
        int x = mtc.first;
        int y = mtc.second;
        if(x > y)   swap(x, y);
        printf("%d %d\n", x, y - N);
    }

    return 0;
}