Problem no.F

#include <iostream>
#include<math.h>
#include<stdio.h>
using namespace std;

int main()
{
    int i,T;
    float x1, y1, x2, y2, ans, a, b;
    cin>>T;
    for(i=1;i<=T;i++)
    {
        cin>>x1>>y1>>x2>>y2;
        a = (x2-x1);
        b = (y2-y1);
        ans = sqrt(a*a+b*b);
       printf("Case %d: %.4f\n",i,ans);
    }
    return 0;
}