#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cctype>
#include <cmath>
#include <string>
#include <algorithm>
#include <vector>
#include <queue>
#include <deque>
#include <set>
#include <stack>
#include <cassert>
using namespace std;

#define PRO "cuplaj"
void OpenFiles(int EVAL)
{
	if(EVAL)
	{
		char input[100] = PRO, output[100] = PRO;
		freopen(strcat(input, ".in"),"r",stdin);
		freopen(strcat(output,".out"),"w",stdout);
	} else
	{
		freopen("test.in","r",stdin);
		freopen("test.out","w",stdout);
	}
}

#define MAX  10001
#define INF 0xffffff

int n,m,st[MAX],dr[MAX],viz[MAX];
vector<int>g[MAX];

bool dfs(int x)
{
	int y;
	if(viz[x])return 0;
	viz[x] = 1;
	for(int i=0;i<g[x].size();i++)
	{
		y = g[x][i];
		if(st[y] == 0 || dfs(st[y]))
		{
			st[y] = x;
			dr[x] = y;
			return 1;
		}
	}
	return 0;
}

void cuplaj()
{
	int nr=0, ok = 1;
	while(ok)
	{
		ok = 0;
		memset(viz,0,sizeof(viz));
		for(int i=1;i<=n;i++)
			if(dr[i]==0 && dfs(i))
			{
				nr++;
				ok = 1;
			}
	}
	printf("%d\n",nr);
	for(int i=1;i<=n;i++)
		if(dr[i])printf("%d %d\n",i,dr[i]);
}

int main(int argv,char *args[])
{
	OpenFiles(argv==0);
	// start
	int e,x,y;
		scanf("%d %d %d",&n,&m,&e);
		for(int i=1;i<=e;i++)
		{
			scanf("%d %d",&x,&y);
			g[x].push_back(y);
		}
	cuplaj();
	return 0;
}