#include <bits/stdc++.h>
using namespace std;
long long M = 1e9 + 7;
long long mpe(long long base, long long exponent, long long modulus) {
  long long result = 1;
  while (exponent > 0) {
    if (exponent % 2 == 1) result = result * base % modulus;
    exponent = exponent >> 1;
    base = base * base % modulus;
  }
  return result;
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(NULL);
  ;
  long long n, a, tmp = 2, fl = 0;
  cin >> n;
  for (long long i = 0; i < n; ++i) {
    cin >> a;
    if (a % 2 == 0) fl = 1;
    tmp = mpe(tmp, a, M);
  }
  long long inv2 = mpe(2, M - 2, M);
  long long inv3 = mpe(3, M - 2, M);
  long long p = tmp * inv2 % M;
  if (fl) {
    p++;
    p %= M;
  } else {
    p = (p - 1 + M) % M;
  }
  p *= inv3;
  p %= M;
  tmp *= inv2;
  tmp %= M;
  cout << p << "/" << tmp;
  return 0;
}
