#include<iostream>
#include<vector>
#include<algorithm>
#include<cmath>
#include<string>
#include<iomanip>
#include<numeric>
#include<queue>
#include<deque>
#include<stack>
#include<set>
#include<map>
#include<random>
using namespace std;
typedef long long ll;
const int mod=998244353;
int main(){
	ll a,b,c,d;
	cin>>a>>b>>c>>d;
	cout<<(a==c||b==d||abs(a-c)+abs(b-d)<=3?1:2)<<endl;
}