#include<bits/stdc++.h>
 using namespace std;
  int main() {
    double Xa,Ya,Xb,Yb,AB;
    cin>>Xa>>Ya;
    cin>>Xb>>Yb;
    AB=sqrt((Xa-Xb)*(Xa-Xb)+(Ya-Yb)*(Ya-Yb));
    printf("%.3f\n",AB);
    return 0; 
  }

#include<bits/stdc++.h> using namespace std; int main() { double Xa,Ya,Xb,Yb,AB; cin>>Xa>>Ya; cin>>Xb>>Yb; AB=sqrt((Xa-Xb)(Xa-Xb)+(Ya-Yb)(Ya-Yb)); printf("%.3f\n",AB); return 0; }

水

#include <iostream>
#include <cmath>
using namespace std;
int main(){
	double a, b, c, d;
	cin >> a >> b >> c >> d;
	printf("%.3f", sqrt((a - c) * (a - c) + (b - d) * (b - d)));
	return 0;
}

水

#include <iostream>
#include <cmath>
using namespace std;
int main(){
	double a, b, c, d;
	cin >> a >> b >> c >> d;
	printf("%.3f", sqrt((a - c) * (a - c) + (b - d) * (b - d)));
	return 0;
}