#include <bits/stdc++.h>
int g(int a, int b) { return b ? g(b, a % b) : a; }
int cc(int a, int b) {
  int r = 0;
  for (; a; r += a % b, a /= b)
    ;
  return r;
}
int main() {
  int a, S = 0, T = 0;
  scanf("%d", &a);
  for (int i = 2; i < a; S += cc(a, i), T++, i++)
    ;
  printf("%d/%d\n", S / g(S, T), T / g(S, T));
  return 0;
}
