#include <bits/stdc++.h>
using namespace std;
long long a, b, c, d, e, i, j, ii, jj, zx, xc, f[29],
    mod = 1000000007LL, pas, G[29][29], kl[17][50009], dp[50009];
long long xar(long long q, long long w) {
  if (w == 0) return 1LL;
  long long qw = xar(q, w / 2);
  if (w % 2 == 0)
    return (qw * qw) % mod;
  else
    return ((qw * qw) % mod * q) % mod;
}
long long ga(long long q, long long w) { return (q * xar(w, mod - 2)) % mod; }
long long win(long long q, long long w) { return G[q][w]; }
int main() {
  ios_base::sync_with_stdio(false), cin.tie(0), cout.tie(0);
  cin >> a;
  for (i = 0; i < a; i++) {
    cin >> f[i];
  }
  for (i = 0; i < a; i++) {
    for (j = 0; j < a; j++) {
      if (i == j) continue;
      G[i][j] = ga(f[i], f[i] + f[j]);
    }
  }
  for (ii = 1; ii < (1 << a); ii++) {
    for (i = 0; i < a; i++) {
      if ((ii & (1 << i)) != 0) continue;
      kl[i][ii] = 1;
      for (j = 0; j < a; j++) {
        if ((ii & (1 << j)) == 0) continue;
        kl[i][ii] *= win(j, i);
        kl[i][ii] %= mod;
      }
    }
  }
  for (ii = 1; ii < (1 << a); ii++) {
    if (__builtin_popcount(ii) == 1) {
      dp[ii] = 0;
      continue;
    }
    for (jj = ii;; jj = ((jj - 1) & ii)) {
      if (jj == 0) break;
      if (jj == ii) continue;
      c = (ii ^ jj);
      zx = 1;
      for (j = 0; j < a; j++) {
        if ((jj & (1 << j)) == 0) continue;
        zx *= kl[j][c];
        zx %= mod;
      }
      dp[ii] += (1 - dp[jj] + mod) * zx;
      dp[ii] %= mod;
    }
  }
  for (ii = 1; ii < (1 << a); ii++) {
    zx = 1;
    for (i = 0; i < a; i++) {
      if ((ii & (1 << i)) == 0) continue;
      for (j = 0; j < a; j++) {
        if ((ii & (1 << j)) != 0) continue;
        zx *= win(i, j);
        zx %= mod;
      }
    }
    c = __builtin_popcount(ii);
    pas += (c * zx) % mod * (1 - dp[ii] + mod);
    pas %= mod;
  }
  cout << pas;
  return 0;
}
