#include <bits/stdc++.h>
using namespace std;
const int Mod = 1e9 + 7;
int qpow(long long a, long long b) {
  long long c = 1;
  while (b) {
    if (b & 1) c = c * a % Mod;
    if (b >>= 1) a = a * a % Mod;
  }
  return c;
}
int n;
long long a;
int p, q;
int main() {
  scanf("%d", &n);
  bool minus = 1;
  q = 2;
  for (int i = 1; i <= n; i++) {
    scanf("%I64d", &a);
    if (!(a & 1)) minus = 0;
    q = qpow(q, a);
  }
  q = q * 500000004ll % Mod;
  if (minus) {
    p = q - 1;
    if (p < 0) p += Mod;
  } else
    p = q + 1;
  p = p * 333333336ll % Mod;
  printf("%d/%d\n", p, q);
  return 0;
}
