#include <fstream>
#include <vector>

std::vector<std::vector<int> > G;
std::vector<int> match;
std::vector<int> vis;

bool DFS(int k) {

	if(vis[k])
		return false;
	vis[k] = 1;
	for(std::vector<int>::iterator v = G[k].begin(); v != G[k].end(); ++v) {
		if(match[*v] == -1 || DFS(match[*v])) { //if DFS(match[*v]) returns true we're sure we've found a path

			match[k] = *v; match[*v] = k;
			return true;
		}
	}
	return false;
}

int main() {

	std::ifstream fin("cuplaj.in");
	std::ofstream fout("cuplaj.out");
	
	int L,R,m;
	fin >> L >> R >> m;
	G.resize(L + R,std::vector<int>());
	match.resize(L + R, -1);
	vis.resize(L + R,0);

	while(m--) {
		int x,y;
		fin >> x >> y;
		--x; --y;
		G[x].push_back(y + L);
		G[y + L].push_back(x);
	}

	int matches = 0;
	for(bool more = true; more;) {
		more = false;
		for(int i=0;i<L;++i) {
			if(match[i] == -1 && DFS(i)) {
				matches ++;
				more = true;
			}
		}
		vis.assign(vis.size(),0);
	}

	fout << matches << '\n';

	for(int i=0;i<L;++i)
	if(match[i] != -1)
		fout << i + 1 << ' ' << match[i] + 1 - L<< '\n';

	return 0;
}