#include <bits/stdc++.h>
const double E = 2.7182818284590452353602874713527;
using namespace std;
long GCD(long a, long b) {
  while (b) b ^= a ^= b ^= a %= b;
  return a;
}
long bs(long num, long b) {
  long res = 0;
  while (b / num != 0) {
    res += b % num;
    b /= num;
  }
  res += b % num;
  return res;
}
int main() {
  long i, sum = 0, cnt = 0, a, rs;
  scanf("%ld", &a);
  for (i = 2; i <= a - 1; i++) {
    cnt++;
    sum += bs(i, a);
  }
  rs = GCD(sum, cnt);
  printf("%ld/%ld\n", sum / rs, cnt / rs);
  return 0;
}
