#include <bits/stdc++.h>
int main() {
  int n, i, s = 0, t = 0, k = 0, z, j, gcd;
  scanf("%d", &n);
  k = n;
  for (i = 2; i <= k - 1; i++) {
    n = k;
    while (n > 0) {
      t = n % i;
      n = n / i;
      s += t;
    }
  }
  z = k - 2;
  for (j = 1; j <= s && j <= z; j++) {
    if (s % j == 0 && z % j == 0) gcd = j;
  }
  printf("%d/%d", (s / gcd), (z / gcd));
  return 0;
}
