#include <stdio.h>
#include <math.h>
int main()
{
    int n,i;
    float x1, x2, y1, y2, distance;
    
    if (scanf("%d", &n) != 1 || n< -10 || n> 10)
    {
        printf("Invalid input\n");
        return 0;
    }
    
    for (i=0; i<n; i++)
    {
        if (scanf("%f %f %f %f", &x1, &y1, &x2, &y2) != 4)
        {
            printf("Invalid input\n");
            
            while (getchar() != '\n');
            continue;
        }
        distance = sqrt (pow((x2-x1),2) + pow ((y2-y1),2));
        printf("%.2f\n",distance);
    }
    return 0;
}