#include<bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i,m,n) for(int i=m; i<n; ++i)
#define repl(i,m,n) for(ll i=m; i<n; ++i)

int main(){
    int a, b, c, d;
    cin >> a >> b >> c >> d;

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