#include<stdio.h>
#include<math.h>

int main(){
    int n;
    if (scanf("%d, &n") != 1)return
    printf("invaild input"),0;
    
    while (n--) {
        double x1,y1,x2,y2;
        if (scanf("%lf %lf %lf %lf",&x1,&y1,&x2,&y2) !=4) 
        return printf("invaild input"),0;
        
        printf("%2lf\n",sqrt((x2-x1)*(x2-x1)+(y2-y1)*(y2-y1)));
    }
    return 0;
}