#include <iostream>
#include <cstring>
#include <algorithm>
using namespace std;
int n,sum;
int gcd(int a, int b) // 欧几里得算法
{
if (a % b == 0) return b;
else return gcd(b,a%b);
}
void solve(int u)
{
int t = n;
while (t)
{
sum += t % u;
t /= u;
}
return ;
}
int main()
{
cin >> n;
for (int i = 2;i < n;i++)
{
solve(i);
}
int c = gcd(sum,n - 2);
cout << sum/c << "/" << (n - 2)/c <<endl;
return 0;
}