#include <bits/stdc++.h>
int gcd(int a, int b) {
  int c;
  while ((c = a % b) != 0) {
    a = b, b = c;
  }
  return b;
}
int sum(int x, int n) {
  int res = 0;
  while (x) {
    res += x % n;
    x /= n;
  }
  return res;
}
int main() {
  int a;
  scanf("%d", &a);
  int i;
  int aa = 0, bb = a - 2;
  for (i = 2; i < a; i++) aa += sum(a, i);
  int t = gcd(aa, bb);
  aa /= t, bb /= t;
  printf("%d/%d\n", aa, bb);
  return 0;
}
