#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); i++)
using namespace std;
typedef long long ll;

int main(){
    cin.tie(0);
    ios::sync_with_stdio(0);

    ll Sx, Sy, Tx, Ty; cin >> Sx >> Sy >> Tx >> Ty;
    if(Sx == Tx || Sy == Ty || abs(Sx - Tx) + abs(Sy - Ty) <= 3) {
        cout << 1 << endl;
    } else {
        cout << 2 << endl;
    }
}