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