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

int main(){
    int n;
    
    // Read number of point pairs
    if (scanf("%d", &n)  !=1) {
        printf("Invalid input");
        return 0;
    }
    
    for (int i = 0; i < n; i++) {
        double x1, y1, x2, y2;
        
        // Read coordinates
        if (scanf("%lf %lf %lf %lf", &x1, &y1,
            printf("Invalid input");
            return 0;
        }
        
        // Calculate Euclidean distance
        double distance = sqrt(pow(x2 - x1, 2)
        
        // Print rounded to 2 decimal places
        printf("%.2lf\n", distance);
    }
    
    return 0;
}