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