#include <bits/stdc++.h>
using namespace std;
typedef long long int ll;
typedef unsigned long long ull;

mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
ll myRand(ll B) {
    return (ull)rng() % B;
}
int main(){
	cin.tie(nullptr);
	ios::sync_with_stdio(false);
	int x,y,xx,yy; cin >> x >> y >> xx >> yy;
	if((ll)abs(x-xx)+(ll)abs(y-yy)<=3 or x==xx or yy==y)printf("1\n");
	else printf("2\n");
}