#include <bits/stdc++.h>
int GCD(int m, int n) {
  int r = m % n;
  while (r != 0) {
    m = n;
    n = r;
    r = m % n;
  }
  return n;
}
int main() {
  int A;
  scanf("%d", &A);
  int X = 0, Y = (A - 2);
  for (int base = 2; base < A; ++base) {
    int n = (A), ds = (0);
    while (n != 0) {
      ds += n % base;
      n /= base;
    }
    X += ds;
  }
  int gcd = GCD(X, Y);
  X /= gcd;
  Y /= gcd;
  printf("%d/%d\n", X, Y);
  return 0;
}
