# include<iostream> # include<cstdio> # include<iomanip> # include<cmath> using namespace std; int main(){ int x1,y1,x2,y2,a,b; cin>>x1>>y1>>x2>>y2; a=abs(x1-x2); b=abs(y1-y2); if(a>b){ cout<<a; } else{ cout<<b; } return 0; }