#include <bits/stdc++.h>

using namespace std;

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

const int NMAX = 1e4 + 4;
vector<int> G[NMAX];
int l[NMAX], r[NMAX];
bool viz[NMAX];

bool dfs(const int &u) {
    if(viz[u])
        return false;
    viz[u] = true;
    for(const int &v : G[u])
        if(!r[v]) {
            l[u] = v;
            r[v] = u;
            return true;
        }
    for(const int &v : G[u])
        if(dfs(r[v])) {
            l[u] = v;
            r[v] = u;
            return true;
        }
    return false;
}

int main() {
    int N, M, E;
    fin >> N >> M >> E;
    while(E--) {
        int u, v;
        fin >> u >> v;
        G[u].emplace_back(v);
    }
    for(bool change = true; change; ) {
        change = false;
        memset(viz, false, sizeof(viz));
        for(int node = 1; node <= N; ++node)
            if(!l[node])
                change |= dfs(node);
    }
    int cuplaj = 0;
    for(int i = 1; i <= N; ++i)
        cuplaj += (l[i] > 0);
    fout << cuplaj << '\n';
    for(int i = 1; i <= N; ++i)
        if(l[i] > 0)
            fout << i << ' ' << l[i] << '\n';
}