#include <stdio.h>
#include <math.h>

int main()
{
    int n;
    //read number of point pairs
    if (scanf("%d",&n)!=1)
    {
        printf("invalid input");
        return 0;
    }
    //validate n
    if (n<0||n>10)
    {
        printf("invalid input");
        return 0;
    }
    for (int i=0;i<n;i++)
    {
        double x1,y1,x2,y2;
        //read coordinates
        if(scanf("%Lf%Lf%Lf%Lf",&x1,&y1,&x2,&y2)!=4)
        {
            printf("invalid input");
            return 0;
        }
        //compute ecuclidean distance
        double distance= sqrt((x2-x1)*(x2-x1)+(y2-y1)*(y2-y1));
        //print result rounded to 2 decimals
        printf("%2.Lf",distance);
        if (i<n-1)
        printf("\n");
    }
    return 0;
}