#include <iostream> #include <cmath> using namespace std; int main(){ int x1,y1,x2,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; }