#include <stdio.h>
#include <math.h>
int main() {
	int size, num, r, count = 0;
	scanf("%d %d %d", &size, &num, &r);
	int arr[1000][1000] = {0};
	for (int i = 1; i <= num; i++) {
		int x, y;
		scanf("%d %d", &x, &y);
		for (int j = 1; j <= size; j++) {
			for (int k = 1; k <= size; k++) {
				int dx = x - j;
				int dy = y - k;
				int d = sqrt(dx * dx + dy * dy);
				if (d <= r && arr[j][k] == 0) {
					arr[j][k] = 1;
					count++;
				}
			}
		}
	}
	printf("%d", count);
	return 0;
}