#include<bits/stdc++.h>
#define rep(i,N) for(int i=0;i<(N);i++)
#define rrep(i, n) for (int i = (int)n-1; i >= 0; --i)
#define FOR(i,a,b) for(int i=(a);i<(b);i++)
using namespace std;
const long long MOD = 1e9 + 7;
const long long INF = 1e12;
const int inf = 1e9;
const int mod = 1e9+7;
typedef long long ll;
typedef pair<ll,int> P;
typedef set<int> S;

template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }

__attribute__ ((constructor))
void fastio() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    cout << fixed << setprecision(10);
}

ll abs_(ll a, ll b) { return max(a, b) - min(a, b); }

int main(){
    ll a, b, c, d;
    cin >> a >> b >> c >> d;
    if(a==c || b==d){
        cout << 1 << endl;
        return 0;
    }
    if(abs_(c, a) + abs_(d, b) <= 3){
        cout << 1 << endl;
        return 0;
    }
    cout << 2 << endl;
    return 0;
}