#include<bits/stdc++.h>
using namespace std;

int main()
{
    ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
    int x1,y1,x2,y2;
    cin >> x1 >> y1 >> x2 >> y2;
    if(abs(x1-x2)==abs(y1-y2))
        cout << 1;
    else if(x1==x2 || y1==y2)
        cout << 2;
    else
        cout << 0;
}