#include <bits/stdc++.h>
using namespace std;
int A;
int conv(int x, int base) {
  int ans = 0;
  while (x) {
    ans += x % base;
    x /= base;
  }
  return ans;
}
int gcd(int a, int b) {
  if (!b) {
    return a;
  }
  return gcd(b, a % b);
}
int main() {
  cin >> A;
  int s = 0;
  int d = A - 2;
  for (int i = 2; i < A; ++i) {
    s += conv(A, i);
  }
  int GCD = gcd(s, d);
  cout << s / GCD << "/" << d / GCD << endl;
}
