#include <fstream>
#include <vector>
#include <queue>
using namespace std;

const int inf = 1e9;
int n, m, e;
vector<int> a[10005];
int d[10005], l[10005], r[10005];

bool bfs() {
    queue<int> q;
    for(int i = 1; i <= n; ++i) {
        if(!l[i]) {
            d[i] = 0;
            q.push(i);
        } else {
            d[i] = inf;
        }
    }
    d[0] = inf;
    while(!q.empty()) {
        int u = q.front(); q.pop();
        if(d[u] < d[0]) {
            for(int v : a[u]) {
                if(d[r[v]] == inf) {
                    d[r[v]] = d[u] + 1;
                    q.push(r[v]);
                }
            }
        }
    }
    return d[0] != inf;
}

bool dfs(int u) {
    if(u) {
        for(int v : a[u]) {
            if(d[r[v]] == d[u] + 1 && dfs(r[v])) {
                l[u] = v;
                r[v] = u;
                return 1;
            }
        }
        d[u] = inf;
        return 0;
    }
    return 1;
}

int main() {
    ifstream f("cuplaj.in");
    ofstream g("cuplaj.out");
    f >> n >> m >> e;
    for(int i = 1; i <= e; ++i) {
        int x, y;
        f >> x >> y;
        a[x].push_back(y);
    }
    int sol = 0;
    while(bfs()) {
        for(int i = 1; i <= n; ++i) {
            if(!l[i] && dfs(i)) {
                sol++;
            }
        }
    }
    g << sol << "\n";
    for(int i = 1; i <= n; ++i) {
        if(l[i]) {
            g << i << " " << l[i] << "\n";
        }
    }
    return 0;
}