#include <bits/stdc++.h>
using namespace std;
int main() {
  int a;
  int count = 0;
  int cc = 0;
  int dd;
  cin >> a;
  for (int i = 2; i <= a - 1; i++) {
    int b = a;
    while (b / i != 0) {
      count += b % i;
      b = b / i;
    }
    count += b;
    cc++;
  }
  if (a < count)
    dd = a;
  else
    dd = count;
  for (int i = dd; i > 0; i--) {
    if (count % i == 0 && cc % i == 0) {
      count = count / i;
      cc = cc / i;
      break;
    }
  }
  cout << count << '/' << cc << endl;
  return 0;
}
