#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); ++i)
#define srep(i,s,t) for (int i = s; i < t; ++i)
#define drep(i,n) for(int i = (n)-1; i >= 0; --i)
using namespace std;
typedef long long int ll;
typedef pair<int,int> P;
#define yn {puts("Yes");}else{puts("No");}
#define MAX_N 200005

int main() {
    int x, y, a, b;
    cin >> x >> y >> a >> b;
    int ans = abs(x) + abs(y);
    if(x == 0 && a == 0){
        if(0 < b && b < y)ans += 2;
        if(b < 0 && y < b)ans += 2;
    }
    if(y == 0 && b == 0){
        if(0 < a && a < x)ans += 2;
        if(a < 0 && x < a)ans += 2;
    }
    cout << ans << endl;
}