#include<iostream> #include<cstdio> #include<cmath> using namespace std; int main(){ double x1,x2,y1,y2,AB; cin>>x1>>y1>>x2>>y2; AB=sqrt(((x1-x2)*(x1-x2))+((y1-y2)*(y1-y2))); printf ("%.0f\n",AB); return 0; }