#include <stdio.h>
#include <math.h>

int main(){

	int x1,x2,y1,y2;
	scanf("%d%d%d%d",&x1,&y1,&x2,&y2);
	int brk=0;
	if((x1==y1 && x2==y2)||(abs(x1-x2)==abs(y1-y2)))
		brk = 1;
	else if(x1==x2 || y1==y2)
		brk = 2;
	else
		brk = 0;
		
	printf("%d",brk);
	return 0;
}