#include <bits/stdc++.h>
using namespace std;
const int mod = 1e9 + 7;
int add(int x, int y) {
  x += y;
  if (x >= mod) x -= mod;
  return x;
}
int mul(long long x, long long y) { return x * y % mod; }
int bin(long long x, long long a) {
  long long y = 1;
  while (a) {
    if (a & 1) y = mul(y, x);
    x = mul(x, x);
    a >>= 1;
  }
  return y;
}
void kill() {
  long long pw = 2;
  long long a = mod - 1;
  int n;
  cin >> n;
  for (int i = 0; i < n; ++i) {
    long long x;
    cin >> x;
    pw = bin(pw, x);
    a = bin(a, x);
  }
  long long p = add(mul(pw, bin(2, mod - 2)), a);
  p = mul(p, bin(3, mod - 2));
  long long q = mul(pw, bin(2, mod - 2));
  cout << p << "/" << q << endl;
}
int main() {
  cout.precision(20);
  cout << fixed;
  ios_base::sync_with_stdio(false);
  kill();
}
