from fractions import Fraction

N = int(input())
Z = [int(s) for s in input().split()]

gr = Fraction(1,1)
theta = [Fraction(1,1)]
for i in range(N-1):
	theta.append(theta[i]*Fraction(Z[i], Z[i+1]))
	gr *= theta[i]/theta[i+1];
print(str(gr.numerator)+'/'+str(gr.denominator))