N=int(input())
x,y,z=map(float,input().split())
P=[tuple(map(float,input().split())) for i in range(N)]

ANS=0

for i in range(N):
    for j in range(i+1,N):
        for k in range(j+1,N):
            x0,y0,z0=P[i]
            x1,y1,z1=P[j]
            x2,y2,z2=P[k]

            a1,a2,a3=x1-x0,y1-y0,z1-z0
            b1,b2,b3=x2-x0,y2-y0,z2-z0
            
            a=a2*b3-a3*b2
            b=a3*b1-a1*b3
            c=a1*b2-a2*b1

            ANS+=abs(a*(x-x0)+b*(y-y0)+c*(z-z0)+1)/(a*a+b*b+c*c)**(1/2)

print(ANS)