#include<stdio.h>
#include<math.h>
int main() {
    int n;                              
    double a,b,c,d;
    (scanf("%d",&n)?n<-10||n>10?puts("Invalid input"):0:puts("Invalid input");
    while(n--){if(scanf("%f %f %f %f",&a, &b, &c, &d) !=4){puts("Invalid input");
    return 0;}
     printf("%.2f\n",hypot(c-a),(d-b));
     return 0;}