#include <bits/stdc++.h>
const long long mod = 1000000007;
using namespace std;
long long x, val;
bool ok = 1;
long long k, i;
long long put(long long b, long long e) {
  long long ret = 1;
  while (e) {
    if (e & 1) ret = (ret * b) % mod;
    b = (b * b) % mod;
    e >>= 1;
  }
  return ret;
}
int main() {
  cin >> k;
  val = 2;
  for (i = 1; i <= k; i++) {
    cin >> x;
    if ((x & 1) == 0) ok = 0;
    val = put(val, x);
  }
  val = (val * put(2, mod - 2)) % mod;
  if (ok)
    cout << ((val - 1) * put(3, mod - 2)) % mod << '/' << val;
  else
    cout << ((val + 1) * put(3, mod - 2)) % mod << '/' << val;
  return 0;
}
