#include <bits/stdc++.h>
using namespace std;
int inv(int v) {
  return v <= 1 ? v
                : (1000000007) - (long long)inv((1000000007) % v) *
                                     ((1000000007) / v) % (1000000007);
}
struct mint {
  int v;
  mint() = default;
  mint(long long v) : v((v % (1000000007) + (1000000007)) % (1000000007)) {}
  mint& operator+=(mint a) {
    v = (v + a.v) % (1000000007);
    return *this;
  }
  mint& operator-=(mint a) {
    v = (v - a.v + (1000000007)) % (1000000007);
    return *this;
  }
  mint& operator*=(mint a) {
    v = ((long long)v * a.v) % (1000000007);
    return *this;
  }
  mint& operator/=(mint a) {
    v = ((long long)v * inv(a.v)) % (1000000007);
    return *this;
  }
  friend mint operator+(mint a, mint b) { return mint(a.v + b.v); }
  friend mint operator-(mint a, mint b) { return mint(a.v - b.v); }
  friend mint operator*(mint a, mint b) { return mint((long long)a.v * b.v); }
  friend mint operator/(mint a, mint b) {
    return mint((long long)a.v * inv(b.v));
  }
};
mint pow(mint base, long long exponent) {
  if (exponent <= 0) {
    return 1;
  }
  mint ret = 1;
  while (exponent) {
    if (exponent & 1) {
      ret *= base;
    }
    exponent >>= 1;
    base = base * base;
  }
  return ret;
}
int main() {
  std::ios::sync_with_stdio(false);
  int n;
  while (cin >> n) {
    vector<int> w(n);
    for (int i = 0; i < n; ++i) {
      cin >> w[i];
    }
    vector<vector<mint>> a(n, vector<mint>(n));
    for (int i = 0; i < n; ++i) {
      for (int j = 0; j < n; ++j) {
        a[i][j] = mint(w[i]) / mint(w[i] + w[j]);
      }
    }
    vector<vector<mint>> g(1 << n, vector<mint>(n));
    for (int mask = 0; mask < (1 << n); ++mask) {
      for (int i = 0; i < n; ++i) {
        g[mask][i] = 1;
        for (int j = 0; j < n; ++j) {
          if (mask & (1 << j)) {
            g[mask][i] *= a[i][j];
          }
        }
      }
    }
    vector<mint> f(1 << n);
    for (int mask = 1; mask < (1 << n); ++mask) {
      f[mask] = 1;
      for (int sub_mask = mask; sub_mask > 0;
           sub_mask = ((sub_mask - 1) & mask)) {
        if (sub_mask < mask) {
          mint val = f[sub_mask];
          int other_mask = mask - sub_mask;
          for (int i = 0; i < n; ++i) {
            if (sub_mask & (1 << i)) {
              val *= g[other_mask][i];
            }
          }
          f[mask] -= val;
        }
      }
    }
    mint result = 0;
    for (int mask = 1; mask < (1 << n); ++mask) {
      int count = 0;
      for (int i = 0; i < n; ++i) {
        if (mask & (1 << i)) {
          ++count;
        }
      }
      mint val = f[mask] * mint(count);
      int other_mask = (1 << n) - 1 - mask;
      for (int i = 0; i < n; ++i) {
        if (mask & (1 << i)) {
          val *= g[other_mask][i];
        }
      }
      result += val;
    }
    printf("%d\n", result.v);
  }
  return 0;
}
