#include <bits/stdc++.h>
using namespace std;
long long mult(long long a, long long b) {
  long long divs = 1;
  long long res = 0;
  for (long long i = 0; i < divs; i++) {
    long long cur = a / divs;
    if (i < a % divs) cur += 1;
    res = (res + cur * b) % (1L * 1000000007L);
  }
  return res;
}
long long binpow(long long exp, long long root) {
  long long prod = 1;
  long long mul = root;
  while (exp > 0) {
    if (exp % 2) prod = mult(prod, mul);
    mul = mult(mul, mul);
    exp /= 2;
  }
  return prod;
}
int main() {
  std::ios::sync_with_stdio(false);
  cin.tie(0);
  long long n;
  cin >> n;
  long long prod = 2;
  bool isEven = false;
  for (long long i = 0; i < n; i++) {
    long long a;
    cin >> a;
    if (a % 2 == 0) isEven = true;
    prod = binpow(a, prod);
  }
  prod = (prod * binpow(1000000007L - 2, 2)) % ((1L * 1000000007L));
  long long top =
      ((prod + isEven - !isEven) * binpow(1000000007L - 2, 3)) % 1000000007L;
  prod = (prod) % 1000000007L;
  cout << top << "/" << prod << endl;
}
