#include <iostream>
#include <cmath>
#include <iomanip>
using namespace std;

int mani()  {
    int n;
    //check if n is valid integer
    if (!(cin >> n)) {
        cout << "Invalid input";
        return 0;
    }
    for (int i=0; i < n; i++)  {
        double x1, y1, x2, y2;
        
        // check if coordinates are valid
        if (!(cin >> x1 >> y1 >> x2 >>y2))  {
            return 0;
        }
        double distance = sqrt((x2 - x1) * (x2 - x1) + (y2 - y1) * (y2 - y1));
        
        cout << fixed << setprecision(2) << distance ;
    }
    return 0;
}