#include <bits/stdc++.h>
using namespace std;
const int N = 2e5 + 10, mod = 1e9 + 7;
int pw(int x, int y) {
  int ret = 1;
  for (; y; y /= 2) {
    if (y & 1) {
      ret = 1ll * ret * x % mod;
    }
    x = 1ll * x * x % mod;
  }
  return ret;
}
void solve() {
  int n;
  cin >> n;
  int a[n], w[n][n];
  for (int i = 0; i < n; i++) {
    cin >> a[i];
    for (int j = 0; j < i; j++) {
      w[i][j] = 1ll * a[i] * pw(a[i] + a[j], mod - 2) % mod;
      w[j][i] = (1 - w[i][j] + mod) % mod;
    }
  }
  int win[n][1 << n];
  for (int i = 0; i < n; i++) {
    win[i][0] = 1;
    for (int j = 1; j < (1 << n); j++) {
      if ((1 << i) & j) {
        continue;
      }
      win[i][j] = 1;
      for (int k = 0; k < n; k++) {
        if ((1 << k) & j) {
          win[i][j] = 1ll * win[i][j] * w[i][k] % mod;
        }
      }
    }
  }
  int dp[1 << n];
  int ans = 0;
  for (int i = 1; i < (1 << n); i++) {
    dp[i] = 1;
    for (int j = (i - 1) & i; j > 0; j = (j - 1) & i) {
      int val = dp[j];
      for (int k = 0; k < n; k++) {
        if ((1 << k) & j) {
          val = 1ll * val * win[k][i ^ j] % mod;
        }
      }
      dp[i] -= val;
      if (dp[i] < 0) {
        dp[i] += mod;
      }
    }
    int add = dp[i];
    for (int j = 0; j < n; j++) {
      if ((1 << j) & i) {
        add = 1ll * add * win[j][((1 << n) - 1) ^ i] % mod;
      }
    }
    ans += 1ll * add * __builtin_popcount(i) % mod;
    if (ans >= mod) {
      ans -= mod;
    }
  }
  cout << ans;
}
int32_t main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  int t = 1;
  int cur = 1;
  while (t--) {
    solve();
  }
  return 0;
}
