#include <bits/stdc++.h>
using namespace std;
int conv(int x, int base) {
  if (x > 0)
    return x % base + conv(x / base, base);
  else
    return 0;
}
int GCD(int a, int b) { return !b ? a : GCD(b, a % b); }
int main() {
  int A;
  cin >> A;
  int top = 0, bot = A - 2;
  for (int t = 2; t < A; ++t) {
    top += conv(A, t);
  }
  int div = GCD(top, bot);
  top /= div;
  bot /= div;
  cout << top << '/' << bot;
}
