#include<stdio.h>
#include<math.h>
int main() {
    int n;
    if (scanf("%d", &n) != 1) {
        printf("Invalid input");
        return 0;
    }
    for (int i = 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;
}