#include<iostream>
#include<cstdio>
#include<cmath>
using namespace std;
class CPoint{
private:
	int x, y;
public:
	CPoint(){}
	CPoint(int xx, int yy):x(xx),y(yy){}
	~CPoint(){}
	double operator-(CPoint c);
};
double CPoint::operator-(CPoint c)
{
	return sqrt((x-c.x)*(x-c.x) + (y-c.y)*(y-c.y));
}
int main()
{
	int m;
	cin >> m;
	while (m--) {
		int x, y;
		cin >> x >> y;
		CPoint a(x,y);
		cin >> x >> y;
		CPoint b(x,y);
		double dis = a - b;
		printf("%.2f\n", dis);
	}
	return 0;
}