#include <bits/stdc++.h>
using namespace std;
int main() {
  int a = 0;
  int b = 0;
  int n;
  cin >> n;
  b = n - 2;
  int chisla[10] = {0};
  int k = 1;
  int l = n;
  for (int i = 2; i < n; i++) {
    k = 1;
    l = n;
    chisla[9] = l % i;
    l = l / i;
    chisla[8] = l % i;
    l = l / i;
    chisla[7] = l % i;
    l = l / i;
    chisla[6] = l % i;
    l = l / i;
    chisla[5] = l % i;
    l = l / i;
    chisla[4] = l % i;
    l = l / i;
    chisla[3] = l % i;
    l = l / i;
    chisla[2] = l % i;
    l = l / i;
    chisla[1] = l % i;
    l = l / i;
    chisla[0] = l % i;
    l = l / i;
    a = a + chisla[0] + chisla[1] + chisla[2] + chisla[3] + chisla[4] +
        chisla[5] + chisla[6] + chisla[7] + chisla[8] + chisla[9];
    for (int j = 0; j < 10; j++) {
      chisla[j] = 0;
    }
  }
  for (int i = b; i > 1; i--) {
    if ((a % i == 0) && (b % i == 0)) {
      a = a / i;
      b = b / i;
      break;
    }
  }
  cout << a << "/" << b;
}
