#include <cstdio>
#include <algorithm>
#include <cstring>

using namespace std;

inline int next_int() {int d;scanf("%d", &d);return d;}

const int V = 10000;
const int E = 100000;

int ec, eb[V], en[E], et[E];
int n, m, XY[V], YX[V];
bool seen[V];

bool dfs(int u) {
	for (int e = eb[u]; e != -1; e = en[e]) {
		int v = et[e];
		if (!seen[v]) {
			seen[v] = true;
			if (YX[v] == -1 || dfs(YX[v])) {
				XY[u] = v;
				YX[v] = u;
				return true;
			}
		}
	}
	return false;
}

int main() {
	freopen("cuplaj.in", "r", stdin);
	freopen("cuplaj.out", "w", stdout);
	memset(eb, -1, sizeof eb);
	memset(XY, -1, sizeof XY);
	memset(YX, -1, sizeof YX);
	int n = next_int();
	int m = next_int();
	int e = next_int();
	for (int i = 0; i < e; i++) {
		int u = next_int() - 1;
		int v = next_int() - 1;
		et[ec] = v;
		en[ec] = eb[u];
		eb[u] = ec++;
	}
	int ans = 0;
	for (int i = 0; i < n; i++) {
		memset(seen, 0, sizeof seen);
		ans += dfs(i);
	}
	printf("%d\n", ans);
	for (int i = 0; i < n; i++) {
		if (XY[i] != -1) {
			printf("%d %d\n", i + 1, XY[i] + 1);
		}
	}
	return 0;
}