#include <algorithm>
#include <cassert>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <iostream>
#include <numeric>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <functional>
#include <iomanip>
using namespace std;
using ll = long long;

const ll mod = 1000000007;
struct mint {
  ll x;
  mint(ll x_ = 0) : x((x_ % mod + mod) % mod) {}
  mint operator-() const { return mint(-x); }
  mint &operator+=(const mint &a) { if ((x += a.x) >= mod) x -= mod; return *this; }
  mint &operator-=(const mint &a) { if ((x += mod - a.x) >= mod) x -= mod; return *this; }
  mint &operator*=(const mint &a) { (x *= a.x) %= mod; return *this; }
  mint operator+(const mint &a) const { mint res(*this); return res += a; }
  mint operator-(const mint &a) const { mint res(*this); return res -= a; }
  mint operator*(const mint &a) const { mint res(*this); return res *= a; }
  mint pow(ll t) const { if (!t) return 1; mint a = pow(t >> 1); a *= a; if (t & 1) a *= *this; return a; }
  mint inv() const { return pow(mod - 2); }
  mint &operator/=(const mint &a) { return (*this) *= a.inv(); }
  mint operator/(const mint &a) const { mint res(*this); return res /= a; }
  auto operator<=>(const mint&) const = default;
  friend ostream &operator<<(ostream &os, const mint &m) { os << m.x; return os; }
  friend istream &operator>>(istream &is, mint &m) { is >> m.x; return is; }
};

class range {private: struct I{int x;int operator*(){return x;}bool operator!=(I& lhs){return x<lhs.x;}void operator++(){++x;}};I i,n;
public:range(int n_):i({0}),n({n_}){}range(int i_,int n_):i({i_}),n({n_}){}I& begin(){return i;}I& end(){return n;}};

vector<mint> fact, invfact;
void prepare(int n) {
  fact.resize(n + 1);
  invfact.resize(n + 1);
  fact[0] = 1;
  for (int i : range(n)) fact[i + 1] = fact[i] * (i + 1);
  for (int i : range(n + 1)) invfact[i] = fact[i].inv();
}

mint combin(int n, int r) {
  if (r > n) return mint(0);
  return fact[n] * invfact[r] * invfact[n - r];
}

template<typename T, typename U> ostream& operator<<(ostream& os, const pair<T, U>& p){ return os << "{" << p.first << ", " << p.second << "}"; }
template<typename T> ostream& operator<<(ostream& os, const vector<T>& obj) { os << "{"; for (const auto& e : obj) os << e << ", "; return os << "}"; }
template<typename T> ostream& operator<<(ostream& os, const set<T>& obj) { os << "set{"; for (const auto& e : obj) os << e << ", "; return os << "}"; }
template<typename T, typename U> ostream& operator<<(ostream& os, const map<T, U>& obj) { os << "map{"; for (const auto& e : obj) os << e << ", "; return os << "}"; }
template<typename T> void take(vector<T>& vec, int n) { vec.resize(n); for (int i = 0; i < n; ++i) cin >> vec[i]; }

#ifdef ONLINE_JUDGE
#define dump(expr) ;
#else
#define dump(expr) { cerr << "\033[33m#L" << __LINE__ << ": " << expr << "\033[39m" << endl; }
#endif

namespace solver {

template<typename T1, typename T2> struct In2 {
  T1 a; T2 b;
  friend std::istream& operator>>(std::istream& is, In2& obj) { T1 t1; T2 t2; is >> t1 >> t2; obj = {t1, t2}; return is; }
};

template<typename T1, typename T2, typename T3> struct In3 {
  T1 a; T2 b; T3 c;
  friend std::istream& operator>>(std::istream& is, In3& obj) { T1 t1; T2 t2; T3 t3; is >> t1 >> t2 >> t3; obj = {t1, t2, t3}; return is; }
};

int n;
vector<int> vs;

void read() {
  cin >> n;
  take(vs, n);
}

using RetType = mint;

RetType run() {
  prepare(60);

  vector<pair<int, int>> segs;  // (B[i], len[i])
  {
    int len = 0, prev = 0;
    for (int i : range(n)) {
      len++;
      if (vs[i] >= 0) {
        if ((prev | vs[i]) != vs[i]) {
          dump("broken");
          return 0;
        }
        segs.emplace_back(vs[i], len);
        len = 0;
        prev = vs[i];
      }
    }
  }

  mint res = 1;

  int prev = 0;
  for (auto [b, len] : segs) {
    int target = __builtin_popcount(b);
    if (target == prev) {
      res *= mint(2).pow(target).pow(len) - 1;
      continue;
    }

    // dp
    vector<mint> dp(target + 1);
    dp[prev] = 1;

    dump(len << " " << prev << " -> " << target)

    for ([[maybe_unused]] int it : range(len)) {
      vector<mint> next(target + 1);
      for (int fr : range(prev, target + 1))
      for (int to : range(fr, target + 1)) {
        mint ways = mint(2).pow(fr) * combin(target - fr, to - fr);
        if (fr == to) ways -= 1;
        next[to] += dp[fr] * ways;
      }
      dp.swap(next);

      dump(dp);
    }

    res *= dp[target];

    prev = target;
  }

  return res;
}

}  // namespace

template <typename F>
void run(F f) { if constexpr (std::is_same_v<decltype(f()), void>) f(); else cout << f() << endl; }

int main(int argc, char** argv) {
  cerr << fixed << setprecision(12);
  cout << fixed << setprecision(12);
  int testcase = 1;
  if (argc > 1) testcase = atoi(argv[1]);
  while (testcase--) {
    solver::read();
  }
  run(solver::run);
}