#include <cstdio>
#include <vector>
#include <algorithm>

using namespace std;

FILE *f=fopen("cuplaj.in","r");
FILE *g=fopen("cuplaj.out","w");

class BipartiteMatcher{
public:

	vector<int> L,R;
	vector< vector<int> > graph;

private:

	vector<bool> viz;
	bool pair_up(int nod){
		if(viz[nod]){
			return 0;
		}
		viz[nod] = 1;
		
		for(auto it:graph[nod]){
			if(!R[it]){
				R[it] = nod;
				L[nod] = it;
				return 1;
			}
		}
		
		for(auto it:graph[nod]){
			if(pair_up(R[it])){
				R[it] = nod;
				L[nod] = it;
				return 1;
			}
		}
		return 0;
	}
	
public:

	BipartiteMatcher(int n,int m){
		graph.resize(n + 1);
		L.resize(n + 1);
		R.resize(m + 1);
		viz.resize(n + 1);
	}
	
	void add_edge(int u,int v){
		graph[u].push_back(v);
	}
	
	int max_match(){
		int ans = 0;
		bool ok = 1;
		fill(L.begin(),L.end(),0);
		fill(R.begin(),R.end(),0);
		while(ok){
			ok = 0;
			fill(viz.begin(),viz.end(),0);
			for(int i = 1;i < (int)L.size();i++){
				if(!L[i] && pair_up(i)){
					ans++;
					ok = 1;
				}
			}
		}
		return ans;
	}
};

int N,M,K;

int main()
{
    fscanf(f,"%d%d%d",&N,&M,&K);
	
	BipartiteMatcher matcher(N + 1,M + 1);
	
    for(int i=1;i<=K;i++)
    {
        int x,y;
        fscanf(f,"%d%d",&x,&y);
		matcher.add_edge(x,y);
    }

    fprintf(g,"%d\n",matcher.max_match());
    for(int i=1;i<=N;i++)
        if(matcher.L[i])
            fprintf(g,"%d %d\n",i,matcher.L[i]);
    fclose(f);
    fclose(g);
    return 0;
}