def gcd(a, b):
    if (a == 0):
        return b
    return gcd(b%a, a)

N = input()
a, b = 1, 1
z = map(int, raw_input().split())
for i in range(N-1):
    c, d = z[i], z[i+1]
    g = gcd(min(z[i], z[i+1]), max(z[i], z[i+1]))
    c /= g
    d /= g
    a *= d
    b *= c

print "%d/%d" % (a, b)