#include <bits/stdc++.h>
using namespace std;
int gcd(int a, int b) {
  if (b == 0) return a;
  return gcd(b, a % b);
}
int main() {
  int a, i, temp;
  long long int sum = 0, n, fra;
  cin >> a;
  for (i = 2; i <= a - 1; i++) {
    temp = a;
    while (temp > 0) {
      sum += temp % i;
      temp = temp / i;
    }
  }
  temp = a - 2;
  fra = gcd(sum, temp);
  while (fra != 1) {
    sum = sum / fra;
    temp = temp / fra;
    fra = gcd(sum, temp);
  }
  cout << sum << "/" << temp << endl;
}
