#include<cstdio>
#include<iostream>
#include<cmath>
int main()
{
double a,b,c,d,m;
int t;
scanf("%d",&t);
while(t--)
{
scanf("%lf%lf%lf%lf",&a,&b,&c,&d);
m=sqrt((a-c)*(a-c)+(b-d)*(b-d));
printf("%.1f
",m);
}
}
/*f(x, y, m, n) = sqrt(x*x + y*y + m*m + n*n - 2*m*x - 2*n*y)
= sqrt(（x-m）^2+(y-n)^2)相当于距离
而 f(x, y, a, b) + f(x, y, c, d)的最小值则为点（a，b）到点（c，d）的距离，即是求 f(a, b, c, d)
*/