#include <bits/stdc++.h>
using namespace std;
const double PI = acos(-1.0);
const double eps = 1e-11;
int countbit(int n) { return (n == 0) ? 0 : 1 + countbit(n & (n - 1)); }
int lowbit(int n) { return n & (n ^ (n - 1)); }
string toString(long long v) {
  ostringstream sout;
  sout << v;
  return sout.str();
}
string toString(int v) {
  ostringstream sout;
  sout << v;
  return sout.str();
}
int Rand16() { return rand(); }
int Rand32() { return rand() * rand(); }
double DRand() { return (double)rand() / RAND_MAX; }
int RandRange(int f, int r) { return f + (int)(DRand() * (r - f) + 0.5); }
int gcd(int a, int b) { return b ? gcd(b, a % b) : a; }
int main() {
  int n;
  cin >> n;
  int i, j;
  int ans = 0;
  for (i = 2; i < n; i++) {
    int tmp = n;
    while (tmp) ans += tmp % i, tmp /= i;
  }
  int d = gcd(ans, n - 2);
  int A = ans / d;
  int B = (n - 2) / d;
  cout << A << "/" << B << endl;
  return 0;
}
