#include <bits/stdc++.h>
using namespace std;
bool a[1001];
int main() {
  int n;
  scanf("%d", &n);
  vector<int> V;
  for (int i = 2; i <= n; i++) {
    if (!a[i]) {
      V.push_back(i);
      for (int j = i * i; j <= n; j += i) a[j] = true;
    }
  }
  int sum = 0;
  for (int i = 2; i <= n - 1; i++) {
    int K = i;
    int S = 0;
    int temp = n;
    while (temp > 0) {
      S += (temp % K);
      temp /= K;
    }
    sum += S;
  }
  int t1, t2;
  t1 = sum;
  t2 = n - 2;
  for (int i = 0; i < V.size(); i++) {
    while (t1 % V[i] == 0 && t2 % V[i] == 0) {
      t1 /= V[i];
      t2 /= V[i];
    }
  }
  printf("%d/%d", t1, t2);
  return 0;
}
