# https://yukicoder.me/problems/no/132

import math

def inner_prod(v1, v2):
    ans =0
    for l in range(3):
        ans += v1[l] * v2[l]
    return ans

def norm2(v1):
    ans =0
    for l in range(3):
        ans += v1[l] * v1[l]
    return ans




def main():
    N  = int(input())
    P = tuple(map(float, input().split()))
    xyz = []
    for _ in range(N):
        p = tuple(map(float, input().split()))
        xyz.append(p)

    answer = 0
    for i in range(N):
        p0 = xyz[i]
        v3 = tuple([P[l] - p0[l] for l in range(3)])
        for j in range(i + 1, N):
            p1 = xyz[j]
            v1 = tuple([p1[l] - p0[l] for l in range(3)])
            for k in range(j + 1, N):
                p2 = xyz[k]
                v2 = tuple([p2[l] - p0[l] for l in range(3)])

                # 係数の計算
                v1v2 = inner_prod(v1, v2)
                v3v1 = inner_prod(v3, v1)
                v3v2 = inner_prod(v3, v2)
                v1_n2 = norm2(v1)
                v2_n2 = norm2(v2)
                v3_n2 = norm2(v3)

                matrix = [
                    [v2_n2, -v1v2],
                    [-v1v2, v1_n2]
                ]
                vector = [v3v1, v3v2]
                new_vector = [0, 0]
                for i in range(2):
                    for j in range(2):
                        new_vector[i] += vector[j] * matrix[i][j]
                d = v2_n2 * v1_n2 - v1v2 ** 2
                ans = v3_n2 - (new_vector[0] * v3v1 / d) - (new_vector[1] * v3v2 / d)
                answer += math.sqrt(ans)
    print(answer)









if __name__ == "__main__":
    main()