#include<stdio.h>
#include<math.h>
int main(){
    int n;
    double x1,y1,x2,y2,distance;
   
    //Read number of point pairs
    if(scanf("%d",&n)!=1){
        printf("Invalid input");
        return 0;
    }
   
    for (int i=0;i<n;i++){
        //Read coordinates
        if(scanf("%if%if%if%if",&x1,&y1,&x2,&y2)!=4){
            printf("Invalid input");
            return 0;
        }
        //calculate Euclidean distance
        distance=sqrt(pow(x2-x1,2)+pow(y2-y1,2));
        //print distance rounded to 2 decimal places
        printf("%2if\n",distance);
        
    }
    return 0;
}