#include<stdio.h>
#include<math.h>
int main()
{
    int n;
    scanf("%d",&n);
    while(n--)
    {
        double x1,y1,x2,y2;
        double dist;
        scanf("%lf %lf %lf %lf",&x1,&y1,&x2,&y2);
        dist=sqrt(pow((x1-x2),2)+pow((y1-y2),2));
         printf("%.2lf\n",dist);
    }
    return 0;
}