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