#include <stdio.h>
#include <stdlib.h>
long long A,B,C,D;

int main(){
scanf("%lld %lld %lld %lld",&A,&B,&C,&D);
if (A == C or B == D or abs(A - C) + abs(B - D) <= 3)
    printf("1");
else
    printf("2");
    }