#include <bits/stdc++.h>
#pragma comment(linker, "/STACK:16777216")
using namespace std;
int a;
int gcd(int a, int b) {
  if (a == 0) return b;
  return gcd(b % a, a);
}
int f(int a, int p) {
  int res = 0;
  while (a) {
    res += a % p;
    a /= p;
  }
  return res;
}
int main() {
  scanf("%d", &a);
  int s = 0;
  for (int i = (2); i < (a); i++) {
    s += f(a, i);
  }
  int ch = s, zn = a - 2;
  int nod = gcd(ch, zn);
  ch /= nod;
  zn /= nod;
  printf("%d/%d\n", ch, zn);
  return 0;
}
