#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(){
    ll A, B, C, D;
    cin >> A >> B >> C >> D;

    int ans = 2;
    if(A == C || B == D) ans = 1;
    if(abs(A - C) + abs(B - D) <= 3) ans = 1;

    cout << ans << endl;
    return 0;
}