#include <iostream>
#include <cmath>
#include <cstdio>
using namespace std;
int main (){
    int n;
    cin>>n;
    while(n--){
        double x1 ,y1,x2,y2;
        cin>>x1>>y1>>x2>>y2;
        double num=(x1-x2)*(x1-x2)+(y1-y2)*(y1-y2);
        printf("%.2lf\n",sqrt(num));
    }
    return 0;
}