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