#include <bits/stdc++.h>
using namespace std;
int main() {
  int a, x, y, z, b = 0, c, d;
  cin >> a;
  for (x = 2; x < a; x++)
    for (z = a; z; b += z % x, z /= x)
      ;
  for (x = b, y = a - 2; z = x % y; x = y, y = z)
    ;
  c = b / y;
  d = ((a - 2) / y);
  cout << c << "/" << d;
  return 0;
}
