"""
 *
 * Author:  Juarez Paulino(coderemite)
 * Email: juarez.paulino@gmail.com
 *
 """
import math
a=int(input())
r=0
for b in range(2,a):
  c=a
  while c:r+=c%b;c//=b
a-=2
d=math.gcd(r,a)
print(f'{r//d}/{a//d}')