#include<stdio.h>

#include<math.h>

int main(){

double x1,y1,x2,y2,m;

int n;

scanf("%d",&n);

while(n--){

scanf("%lf %lf %lf %lf",&x1,&y1,&x2,&y2);

m=(x1-x2)(x1-x2)+(y1-y2)(y1-y2);

m=sqrt(m);

printf("%.2f\n",m);

}

return 0;

}