#include<bits/stdc++.h>
using namespace std;
 
#define debug(x) cerr << #x << ": " << (x) << endl
#define rep(i,a,b) for(int i=(a);i<=(b);i++)
#define dwn(i,a,b) for(int i=(a);i>=(b);i--)
#define pb push_back
#define all(x) (x).begin(), (x).end()
 
#define int long long

signed main(){
	int n; cin>>n;
	vector<int> b={2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47};
	int phi=1, cur=1;
	for(auto e: b){
		if(cur*e<=n){
			cur*=e;
		}
		else break;
		phi*=(e-1);
	}
	debug(cur);
	int x=cur-phi, y=cur;
	int g=__gcd(x, y);
	cout<<x/g<<"/"<<y/g<<endl;
	
	return 0;
}