#include <bits/stdc++.h>
using namespace std;
const int INF = 1e9 + 7;
const int MOD = 1e9 + 7;
const int MAXN = 1e6 + 3;
struct Rcompare {
  bool operator()(pair<int, int> lhs, pair<int, int> rhs) {
    return lhs.first > rhs.first;
  }
};
struct compare {
  bool operator()(pair<int, int> lhs, pair<int, int> rhs) {
    return lhs.first < rhs.first;
  }
};
long long solve(long long x, long long y) {
  if (x == 0) {
    return 1;
  }
  long long ans = 1;
  if (x % 2) {
    ans = y;
  }
  long long z = solve(x / 2, y);
  ans *= z;
  ans %= MOD;
  ans *= z;
  ans %= MOD;
  return ans;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  int m = 333333336;
  int n;
  cin >> n;
  long long x, y = 2;
  bool odd = false;
  for (int i = 0; i < (n); ++i) {
    long long z;
    cin >> z;
    y = solve(z, y);
    y %= MOD;
    if (z % 2 == 0) {
      odd = true;
    }
  }
  y *= 500000004;
  y %= MOD;
  if (odd == false) {
    x = y - 1;
  } else {
    x = y + 1;
  }
  x *= 333333336;
  x %= MOD;
  cout << x << "/" << y;
  return 0;
}
