#include<stdio.h>
int abs(int n)
{
	if (n < 0)
		n *= -1;
	return n;
}
int main()
{
	int a, b, c, d;
	scanf("%d %d %d %d", &a, &b, &c, &d);
	int ans = 2;
	if (a == c)ans = 1;
	if (b == d)ans = 1;
	if (abs(a - c) + abs(b - d) <= 3)ans = 1;
	printf("%d\n", ans);
	return 0;
}