#include <stdio.h>
#include <string.h>
#include <queue>

struct Point
{
	int x, y;
	Point(int x = 0, int y = 0): x(x), y(y) {}
};

typedef std::queue< Point > Queue;

static const int MAXN = 1024;

int n, m, k;
char a[MAXN][MAXN];
Queue q;

void try_put(int x, int y)
{
	if(x < 0 || y < 0 || x >= n || y >= m || a[y][x] != 0)
		return;
	a[y][x] = 1;
	q.push(Point(x,y));
}

void fill(int x, int y)
{
	try_put(x, y);
	while(!q.empty())
	{
		Point p = q.front();
		q.pop();
		try_put(p.x - 1, p.y);
		try_put(p.x + 1, p.y);
		try_put(p.x, p.y - 1);
		try_put(p.x, p.y + 1);
	}
}

int main()
{
	scanf("%d %d %d", &n, &m, &k);
	memset(a, 0, sizeof(a));
	for(int i = 0; i < k; ++ i)
	{
		int x, y;
		scanf("%d %d", &x, &y);
		a[y - 1][x - 1] = -1;
	}

	int count = 0;
	for( int y = 0; y < m; ++ y )
		for( int x = 0; x < n; ++ x )
			if( a[y][x] ==0 )
				fill(x, y), ++ count;

	printf("%d", count);
	return 0;
}