#include<stdio.h>
#include<math.h>
#
int main()
{
    int n;
    if(scanf("%d",&n)!=1||n<=0||n>10||isalpha(n))
    {
        printf("Invalid input");
        return 0;
    }
    for(int i=0;i<n;i++)
    {
        int x1,y1,x2,y2;
        if(scanf("%d %d %d %d",&x1, &y1, &x2, &y2)!=4)
        {
            printf("Invalid input");
            return 0;
        }
        if(x1<-1000||x1>1000||x2<-1000||x2>1000||y1<-1000||y1>1000||y2<-1000||y2>1000)
        {
            printf("Invalid input");
            return 0;
        }
        double dx=x2-x1;
        double dy=y2-y1;
        double d=sqrt(dx*dx + dy*dy);
        printf("%.2f",d);
    }
    return 0;
}