#include <bits/stdc++.h>
using namespace std;
int g;
int f(int k) {
  int h = g, ans = 0;
  while (h) {
    ans += h % k;
    h /= k;
  }
  return ans;
}
int gcd(int k, int m) {
  if (k == 0) return m;
  if (m == 0) return k;
  if (k > m) return gcd(k % m, m);
  return gcd(k, m % k);
}
int main() {
  int b;
  scanf("%d", &g);
  int s = 0;
  for (b = 2; b < g; b++) {
    s += f(b);
  }
  int o = gcd(s, g - 2);
  printf("%d/%d\n", s / o, (g - 2) / o);
  return 0;
}
