# include<iostream> # include<stdio> using namespace std; int main(){ int x1,x2,y1,y2; int n=0,z=0; scanf("%d%d%d%d",&x1,&y1,&x2,&y2); if(x1>x2){ n=x1-x2; }else{ n=x2-x1; } if(y1>y2){ z=y1-y2; }else{ z=y2-y1; } if(n>z){printf("%d",n); }else {printf("%d",z) ; } return 0; }