hdu 2547

#include <iostream>
#include <cstdio>
#include <cmath>

using namespace std;
const static double PI = acos(-1.0);
const static double G = 9.8;

double dist(double x,double y,double xx,double yy)
{
	return sqrt((x-xx)*(x-xx)+(y-yy)*(y-yy));
}

int main()
{  
	int test;
	cin>>test;
	while(test--)
	{
		double x,xx,yy,y;
		scanf("%lf%lf%lf%lf",&x,&y,&xx,&yy);
		printf("%.1lf\n",dist(x,y,xx,yy));
	}
	return 0;
}