#include <bits/stdc++.h>
int convert(int n, int number) {
  if (n == 0)
    return 0;
  else
    return (n % number) + convert(n / number, number);
}
int gcd(int a, int b) {
  if (a % b == 0)
    return b;
  else
    return gcd(b, a % b);
}
int main() {
  int n, p, i, sum = 0;
  scanf("%d", &n);
  for (i = 2; i < n; i++) {
    p = convert(n, i);
    sum = sum + p;
  }
  printf("%d/%d", sum / gcd(sum, (n - 2)), (n - 2) / gcd(sum, (n - 2)));
  return 0;
}
