#include<iostream> #include<cstdio> //scanf()\printf() #include<cstring> #include<cmath> //sqrt()\pow()\abs()\ceil()\floor()\max()\min() using namespace std; int main(){ int a,b,c,d; cin>>a>>b>>c>>d; a=abs(a-c); b=abs(b-d); if(a>b){ cout<<a; } else{ cout<<b; } return 0; }