#include <bits/stdc++.h>
using namespace std;
const int mod = 1e9 + 7;
long long pw(long long a, long long b) {
  long long ans = 1;
  while (b) {
    if (b & 1) ans = ans * a % mod;
    a = a * a % mod;
    b >>= 1;
  }
  return ans;
}
int main() {
  int k;
  long long x;
  long long fz = -1, fm = 2;
  cin >> k;
  for (int i = 1; i <= k; i++) {
    cin >> x;
    fz = pw(fz, x);
    fm = pw(fm, x);
  }
  fm = fm * pw(2, mod - 2) % mod;
  fz = fz * pw(-1, mod - 2) % mod;
  printf("%lld/%lld\n", (fm - fz + mod) % mod * pw(3, mod - 2) % mod, fm);
  return 0;
}
