#include <bits/stdc++.h>
int main() {
  int a = 0, b = 0, c = 2;
  int num, p_num, sum = 0;
  int most;
  int i, m;
  scanf("%d", &num);
  for (i = 2; i < num; i++) {
    for (m = 1; m < num; m = i * m)
      ;
    if (m == num) {
      sum += 1;
    } else {
      m = m / i;
      p_num = num;
      for (m = m; m > 1; m = m / i) {
        sum += p_num / m;
        p_num -= m * (p_num / m);
      }
      sum += p_num;
    }
  }
  num = num - 2;
  while (1) {
    for (i = num; i >= 2; i--) {
      if (sum % i == 0 && num % i == 0) {
        sum /= i;
        num /= i;
      }
    }
    if (i == 1) break;
  }
  printf("%d/%d\n", sum, num);
}
