#include<bits/stdc++.h> using namespace std; int main(){ float x1,x2,y1,y2,ab,b; cin>>x1>>x2>>y1>>y2; ab=(x1-x2)*(x1-x2)+(y1-y2)*(y1-y2); b=sqrt(pow(x1-x2,2)+pow(y1-y2,2)); cout<<int(b); return 0; }