#include <stdio.h>
int itix,itiy,mokuhyoux,mokuhyouy,ans,zans,zansx,zansy;
int main(void) {
  //printf("今の座標と目標の座標教えて:"); 
  scanf("%d  %d  %d  %d",&itix,&itiy,&mokuhyoux,&mokuhyouy);
if(itix == mokuhyoux || itiy == mokuhyouy){
  ans=1;
  printf("%d",ans);
  return 0;
}
if(itix<0){
  itix=itix*-1;
}
if(itiy<0){
  itiy=itiy*-1;
}
if(mokuhyoux<0){
  mokuhyoux=mokuhyoux*-1;
}
if(mokuhyouy<0){
  mokuhyouy=mokuhyouy*-1;
}
zansx = mokuhyoux - itix;
if(zansx<0){
  zansx=zansx*-1;
}
zansy = mokuhyouy - itiy;
if(zansy<0){
  zansy=zansy*-1;
}
zans = zansx+zansy;
if(zansx <= 2 && zansy <= 2 && zans<4){
ans  = 1;
printf("%d",ans);
}

else{
ans = 2;
printf("%d",ans);
}
return 0;
}