#include <bits/stdc++.h>

using namespace std;

ifstream fin("cuplaj.in");
ofstream fout("cuplaj.out");

class Match {
private:
   constexpr static int lim = 10007;
    int N, M, E;
    vector<int>muc[lim];
    bitset<lim>used;
    array<int, lim>boy, gurl;

   public:
       Match() {
           fin >> N >> M >> E;
           fill(begin(boy), end(boy), -1);
           fill(begin(gurl), end(gurl), -1);
           for(int i = 0; i < E; ++i) {
               int x, y;
               fin >> x >> y;
               x--; y--;
               muc[x].push_back(y);
           }
       }
// st baieti dr fete
    bool cupleaza(int vertex, bitset<lim>&used) {
        if(used[vertex]) return false;
        used[vertex] = 1;
        for(auto itr : muc[vertex]) {
            if(boy[itr] == -1) {
                boy[itr] = vertex;
                gurl[vertex] = itr;
                return 1;
            }
        }

        for(auto itr : muc[vertex]) {
            if(cupleaza(boy[itr], used)) {
                boy[itr] = vertex;
                gurl[vertex] = itr;
                return 1;
            }
        }

        return false;
    }

    void Run() {
        bool have = 1;
        while(have) {
              have = false;
              used.reset();
              for(int i = 0; i < N; ++i) {
                 if(gurl[i] != -1) continue;
                 have |= cupleaza(i, used);
              }
        }

        int cat = 0;
        for(int i = 0; i < N; ++i)
            cat += gurl[i] != -1;
        fout << cat << '\n';
        for(int i = 0; i < N; ++i)
            if(gurl[i] != -1)
               fout << i + 1 << ' ' << gurl[i] + 1<< '\n';
    }
};

int main() {
    Match G;
    G.Run();
    return 0;
}