#include <bits/stdc++.h>
#pragma comment(linker, "/STACK:64000000")
using namespace std;
int nod(int a, int b) {
  while ((a != 0) && (b != 0)) {
    if (a > b) {
      a %= b;
    } else {
      b %= a;
    }
  }
  return a + b;
}
int main() {
  int a, s = 0;
  cin >> a;
  for (int i = 2; i < a; i++) {
    int t = 0, j = a;
    while (j != 0) {
      t += (j % i);
      j /= i;
    }
    s += t;
  }
  int s1 = a - 2;
  int nn = nod(s1, s);
  s1 /= nn;
  s /= nn;
  cout << s << '/' << s1;
  return 0;
}
