import math

n = int(input())
px, py, pz = map(float, input().split())
points = []
for _ in range(n):
  xi, yi, zi = map(float, input().split())
  points.append((xi - px, yi - py, zi - pz))

ans = 0.0
for i in range(n - 2):
  xi, yi, zi = points[i]
  for j in range(i + 1, n - 1):
    xj, yj, zj = points[j]
    ux, uy, uz = xj - xi, yj - yi, zj - zi
    for k in range(j + 1, n):
      xk, yk, zk = points[k]
      vx, vy, vz = xk - xi, yk - yi, zk - zi
      nx, ny, nz = uy * vz - uz * vy, uz * vx - ux * vz, ux * vy - uy * vx
      d = abs(- nx * xi - ny * yi - nz * zi) / math.sqrt(nx ** 2 + ny ** 2 + nz ** 2)
      ans += d

print(ans)