#include <iostream>
#include <fstream>
#include <vector>
#include <stack>

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

struct muchie{
    int x, y;
    bool cuplat = false;
}G[100005];

vector<int> A[20005];
stack<pair<int, int> > st; // stiva ce retine un nod si muchia folosita

int main()
{
    int i, n, m, e, x, y, ln, lc, nurm, ct = 0;
    unsigned int j;
    bool sel[20005] = {0}, tempsel[20005] = {0};
    fin >> n >> m >> e;

    for(i = 1; i <= e; i++){
        fin >> x >> y;
        G[i].x = x; G[i].y = n + y;
        A[x].push_back(i);
        A[n + y].push_back(i);
    }

    for(i = 1; i <= n; i++){
        for(j = 0; j < A[i].size(); j++){
            if(!sel[G[A[i][j]].y]){ ct++;
                sel[G[A[i][j]].y] = true;
                G[A[i][j]].cuplat = true;
                sel[i] = true;
                break;
            }
        }
    }

    for(i = 1; i <= n; i++)
        if(!sel[i]){
            st.push(make_pair(i, 0));
            tempsel[i] = true;
            while(!st.empty()){
                ln = st.top().first; lc = st.top().second;
                if(ln <= n){
                    for(j = lc; j < A[ln].size(); j++){
                        if(G[A[ln][j]].cuplat == false){
                            nurm = G[A[ln][j]].y;
                            if(tempsel[nurm]) continue;
                            tempsel[nurm] = true;
                            st.pop();
                            st.push(make_pair(ln, j + 1));//updateaza muchia care a ramas de incercat
                            st.push(make_pair(nurm, 0));
                            break;
                        }
                    }
                    if(j == A[ln].size()) tempsel[st.top().first] = false, st.pop();
                }
                else{
                    for(j = lc; j < A[ln].size(); j++){
                        if(G[A[ln][j]].cuplat == true){
                            nurm = G[A[ln][j]].x;
                            if(tempsel[nurm]) continue;
                            tempsel[nurm] = true;
                            st.pop();
                            st.push(make_pair(ln, j + 1));
                            st.push(make_pair(nurm, 0));
                            break;
                        }
                    }
                    if(j == A[ln].size()) tempsel[st.top().first] = false, st.pop();
                }
                if(!st.empty() && !sel[st.top().first] && st.top().first != i) break;
            }
            if(!st.empty()){ ct++;
                sel[st.top().first] = sel[i] = true;
                tempsel[st.top().first] = false; st.pop();
                while(!st.empty()){
                    x = st.top().first;
                    tempsel[x] = false;
                    j = st.top().second - 1;
                    G[A[x][j]].cuplat = 1 - G[A[x][j]].cuplat;
                    st.pop();
                }
            }
        }
    fout << ct << "\n";
    for(i = 1; i <= e; i++)
        if(G[i].cuplat) fout << G[i].x << " " << G[i].y - n << "\n";

    return 0;
}