#include <iostream> using namespace std; int main(){ int a,b; int c,d; cin>>a>>b>>c>>d; int delx = a-c; int dely = b-d; if (delx<0) delx = -delx; if ( dely<0) dely = -dely; if (delx>dely) cout<<delx; else cout<< dely; return 0; }