#include <stdio.h>
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace atcoder;
using mint = modint1000000007;
using namespace std;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf 1000000001

int main(){
	
	long long a,b,c,d;
	cin>>a>>b>>c>>d;
	
	if(abs(a-c)+abs(b-d)<=3 || a==c || b==d)cout<<1<<endl;
	else cout<<2<<endl;
	
    return 0;
}