#include <bits/stdc++.h>
using namespace std;
int n, s, d;
inline int gcd(const int x, const int y) {
  return (x % y == 0 ? y : gcd(y, x % y));
}
inline void get_num(const int k) {
  register int x = n;
  while (x) {
    s += x % k;
    x /= k;
  }
}
int main() {
  scanf("%d", &n);
  for (register int i = 2; i <= n - 1; i++) get_num(i);
  d = n - 2;
  register int t = gcd(s, d);
  printf("%d/%d", s / t, d / t);
  return 0;
}
