#include <iostream>
#include <iomanip>
#include <cstdio>
#include <stdio.h>
#include <string>
#include <cstring>
#include <cmath>
#include <bits/stdc++.h>
#include <algorithm>
#include <set>
#include <map>
#include <vector>

using namespace std;

#define pb push_back
#define mp make_pair
#define x first
#define y second

typedef long long ll;
typedef long double ld;

const int N = (int) 1e3;
const int INF = (int) 1e9;
const ld EPS = (ld) 1e-9;

ll a1, b1;
ll d[10], a[10];

ll gcd(ll a, ll b){
    if (b == 0)
        return a;
    return gcd(b, a % b);
}

ll slc(ll q1, ll q2, ll p1, ll p2){
    return q1 * p2 + p1 * q2;
}

ll slz(ll q2, ll p2){
    return q2 * p2;
}

void check(ll n, ll x){
    ll cnt = 0;
    ll pr = 1;
    for (ll i = 0; i < n; i++)
        if (d[i] == 1){
            cnt++;
            pr *= a[i];
        }
    if (cnt == x){
        a1 = slc(a1, b1, 1, pr);
        b1 = slz(b1, pr);
        ll nod = gcd(a1, b1);
        a1 /= nod;
        b1 /= nod;
    }
}

void go(ll i, ll n, ll x){
    d[i] = 0;
    if (i == n - 1)
        check(n, x);
    else
        go(i + 1, n, x);
    d[i] = 1;
    if (i == n - 1)
        check(n, x);
    else
        go(i + 1, n, x);
}

int main(){
    ll n, ansa = 0, ansb = 1, nod;
    cin >> n;
    for (ll i = 0; i < n; i++)
        cin >> a[i];
    sort(a, a + n);
    for (ll i = 0; i < n; i++){
        a1 = 0;
        b1 = 1;
        go(0, n, i + 1);
        ll c = 1;
        for (ll j = 0; j < i + 2; j++)
            c *= a[0];
        c *= (i + 1);
        a1 = a1 * c;
        b1 = b1 * (i + 2);
        nod = gcd(a1, b1);
        a1 /= nod;
        b1 /= nod;
        if (i % 2 != 0)
            a1 = -a1;
        ansa = slc(ansa, ansb, a1, b1);
        ansb = slz(ansb, b1);
        nod = gcd(ansa, ansb);
        ansa /= nod;
        ansb /= nod;
    }
    nod = gcd(ansa, ansb);
    if (nod == 0)
        nod = 1;
    cout << ansa / nod << '/' << ansb / nod << endl;
    return 0;
}