#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",&x1,&y1,&x2,&y2)!=4){
         printf("invalid input");
         return 0;
         }
         double distance=sqrt((x2-x1)*(x2-x1)+(y2-y1)*(y2-y1);
         printf("%.2f",distance);
         if (i<n-1)
             printf ("\n");
        }  
        return 0;
    }