#include<stdio.h>
#include<math.h>
int main() {
    int n;
    if (scanf("%d", &n) != 1) {
        printf("Invalid input");
        return 0;
    }
   
    for (int i = 0 ; i < n ; i++){
        double x1, y1, x2, y2;
        if (scanf("%lf %lf %lf %lf", &x1, &y1, &x2, &y2) != 4){
            printf("Invaid input");
            return 0;
        }
        double distance = sqrt(pow(x2 - x1)*(x2-x1)+(y2-y1)*(y2-y1));
        printf("%.2lf\n", distance);
    }
    return 0;
}