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