#include <bits/stdc++.h>
using namespace std;
int n;
int nr, lg;
void solve(int base) {
  int cn = n;
  ++lg;
  while (cn) {
    nr += cn % base;
    cn = cn / base;
  }
}
int cCmmdc(int a, int b) {
  int c;
  while (b) {
    c = a % b;
    a = b;
    b = c;
  }
  return a;
}
int main() {
  cin >> n;
  for (int b = 2; b <= n - 1; ++b) {
    solve(b);
  }
  int x = cCmmdc(nr, lg);
  nr /= x;
  lg /= x;
  cout << nr << '/' << lg << '\n';
  return 0;
}
