from math import gcd

N = int(input())
Z = list(map(int, input().split()))
z0 = Z[0]
mother = 1
daughter = 1
for i in range(1, N):
    mother *= Z[i]
    daughter *= Z[i - 1]
    g = gcd(mother, daughter)
    mother //= g
    daughter //= g
print(str(mother) + "/" + str(daughter))