#include <bits/stdc++.h>
using namespace std;
int fanc(int n, int b) {
  int ans = 0;
  while (n > 0) {
    ans += n % b;
    n /= b;
  }
  return ans;
}
int gcd(int x, int y) { return x ? gcd(y % x, x) : y; }
int main() {
  int n, i, x = 0, y = 0;
  cin >> n;
  for (i = 2; i < n; i++) {
    x += fanc(n, i);
    y++;
  }
  int d = gcd(x, y);
  cout << x / d << '/' << y / d;
}
