#include <stdio.h>
#include <stdlib.h>

int main()
{
	int A, B, C, D, ans = 2;
	scanf("%d %d %d %d", &A, &B, &C, &D);
	if (abs(A - C) + abs(B - D) <= 3) ans = 1;
	else if (A == C || B == D) ans = 1;
	printf("%d\n", ans);
	fflush(stdout);
	return 0;
}