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

ifstream fi("cuplaj.in");
ofstream fo("cuplaj.out");

int n,m,v,viz[10001],x,y,i,j,rs,l[10001],r[10001];
vector <int> g[10001];

int cuplaj(int nod) {
	viz[nod] = 1;

	for (vector <int>::iterator it = g[nod].begin(); it != g[nod].end(); it++) {
		if (!r[*it] || (!viz[r[*it]] && cuplaj(r[*it]))) {
			l[nod] = *it;
			r[*it] = nod;
			return 1;
		}
	}

	return 0;
}

int main() {

	fi >> n >> m >> v;

	for (i = 0; i < v; i++) {
		fi >> x >> y;
		g[x].push_back(y);
	}

	int ok = 1;
	while (ok) {
		ok = 0;
		for (i = 1; i <= n; i++) {
			viz[i] = 0;
		}

		for (i = 1; i <= n; i++) {
			if (!l[i]) {
				if (cuplaj(i)) {
					rs++;
					ok = 1;
				}
			}
			
		}
	}

	fo << rs << endl;

	for (i = 1; i <= n; i++) {
		if (l[i]) {
			fo << i << ' ' << l[i] << endl;
		}
	}

	return 0;
}