#include<bits/stdc++.h> using namespace std; int a,b,c,d; int main(){ cin >> a >> b >> c >> d; int m1 = max(a,c); int m2 = min(a,c); int m3 = max(b,d); int m4 = min(b,d); cout << (m1 - m2) + (m3 - m4); }