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