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