#include<iostream> using namespace std; int main() { int a,b,c,d,h,l; cin>>a>>b>>c>>d; if(a<c) { l=c-a; } else { l=c-b; } if(b<d) { h=d-b; } else { h=b-d; } if(h<0) { h=-h; } if(l<0) { l=-l; } if(h>l) { cout<<h; } else { cout<<l; } return 0; }