#include <bits/stdc++.h>
using namespace std;
long long x = 0;
void solve(int a, int base) {
  while (a != 0) {
    x += (a % base);
    a = a / base;
  }
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  int a, i;
  cin >> a;
  for (i = 2; i < a; i++) {
    solve(a, i);
  }
  a = a - 2;
  for (i = a - 2; i > 1; i--) {
    if ((x % i == 0) && (a % i == 0)) {
      x = x / i;
      a = a / i;
      break;
    }
  }
  cout << x << '/' << a;
  return 0;
}
