## https://yukicoder.me/problems/no/1426

MOD = 10 ** 9 + 7

class CombinationCalculator:
    """
    modを考慮したPermutation, Combinationを計算するためのクラス
    """    
    def __init__(self, size, mod):
        self.mod = mod
        self.factorial = [0] * (size + 1)
        self.factorial[0] = 1
        for i in range(1, size + 1):
            self.factorial[i] = (i * self.factorial[i - 1]) % self.mod
        
        self.inv_factorial = [0] * (size + 1)
        self.inv_factorial[size] = pow(self.factorial[size], self.mod - 2, self.mod)

        for i in reversed(range(size)):
            self.inv_factorial[i] = ((i + 1) * self.inv_factorial[i + 1]) % self.mod

    def calc_combination(self, n, r):
        if n < 0 or n < r:
            return 0

        if r == 0 or n == r:
            return 1
        
        ans = self.inv_factorial[n - r] * self.inv_factorial[r]
        ans %= self.mod
        ans *= self.factorial[n]
        ans %= self.mod
        return ans
    
    def calc_permutation(self, n, r):
        if n < 0 or n < r:
            return 0

        ans = self.inv_factorial[n - r]
        ans *= self.factorial[n]
        ans %= self.mod
        return ans
        

def main():
    N = int(input())
    B = list(map(int, input().split()))

    # あらかじめ必要な項は計算しておく
    combi = CombinationCalculator(N, MOD)
    f_array = [0] * (N + 1)
    f = 1
    f_array[0] = 1
    for i in range(1, N + 1):
        f *= 2
        f %= MOD
        f_array[i] = f
    g_array = [0] * (N + 1)
    for i in range(1, N + 1):
        g_array[i] = (f_array[i] - 1) % MOD


    # 本計算
    array = [0] * 30
    prev = -1
    answer = 1
    for i in range(N):
        if B[i] != -1:
            new_array = [0] * 30
            for j in range(30):
                if B[i] & (1 << j):
                    new_array[j] += 1
            
            ans = 1
            # 長さ
            i0 = i - prev

            f_num = 0
            g_num = 0
            for j in range(30):
                if new_array[j] > 0 and array[j] == 0:
                    g_num += 1
                elif new_array[j] == 0 and array[j] > 0:
                    ans = 0
                elif new_array[j] > 0 and array[j] > 0:
                    f_num += 1

            a = 0            
            for j in range(i0 + 1):
                s = pow(-1, j, MOD)
                s *= combi.calc_combination(i0, j)
                s %= MOD
                s *= pow(f_array[i0 - j], f_num, MOD)
                s %= MOD
                s *= pow(g_array[i0 - j], g_num, MOD)
                s %= MOD
                a += s
                a %= MOD
            ans *= a
            ans %= MOD

            answer *= ans
            answer %= MOD

            for j in range(30):
                array[j] |= new_array[j]
            prev = i

    print(answer)





if __name__ == "__main__":
    main()