hud 2073

#include<stdio.h>
#include<math.h>
int main() {
    int i,j,k,n,m,t;
    double a[220];
    a[0]=0;
    for(i=1;i<=210;i++)
        a[i]=a[i-1]+sqrt(1.0*i*i+1.0*(i-1)*(i-1))+sqrt(1.0*i*i*2);
    int x1,y1,x2,y2;
    scanf("%d",&t);
    while(t--) {
        scanf("%d%d%d%d",&x1,&y1,&x2,&y2);
        
        double r,y;
        if(x1==0&&y1==0)
            r=0;
        else  {
            m=x1+y1-1;
        r=a[m]+sqrt(1.0*m*m+1.0*(m+1)*(m+1))+sqrt(1.0*x1*x1+1.0*(m+1-y1)*(m+1-y1));
        }
        if(x2==0&&y2==0)
            y=0;
        else {
        m=x2+y2-1;
        y=a[m]+sqrt(1.0*m*m+1.0*(m+1)*(m+1))+sqrt(1.0*x2*x2+1.0*(m+1-y2)*(m+1-y2));
        }
        printf("%.3f\n",fabs(y-r));
    }
    return 0;
}