#include <bits/stdc++.h>
using namespace std;
long long _maxi;
long long _myList[1009];
long long _cc = 0;
long long _sigma = 0;
long long Gcd(long long x, long long y) {
  if (y == 0) {
    return x;
  }
  return Gcd(y, x % y);
}
void Transfer(long long number, long long limit) {
  _cc = 0;
  while (number > 0) {
    _myList[_cc] = number % limit;
    _cc++;
    number /= limit;
  }
  for (long long i = 0; i < _cc; i++) {
    _sigma += _myList[i];
  }
}
void CParseIn() { cin >> _maxi; }
void Core() {
  for (long long i = 2; i < _maxi; i++) {
    Transfer(_maxi, i);
  }
}
void CWriteOut() {
  cout << _sigma / Gcd(_sigma, _maxi - 2);
  cout << "/";
  cout << (_maxi - 2) / Gcd(_sigma, _maxi - 2) << endl;
}
signed main() {
  CParseIn();
  Core();
  CWriteOut();
  return 0;
}
