# -*- coding: utf-8 -*-
"""
Created on Sun Aug  1 14:59:24 2021

@author: sumitacchan
"""

N = int(input())
P = list(map(int, input().split()))
mod = 10**9+7

n0 = 0
n1 = 0
n2 = 0
for x in P:
    if x < 50:
        n0 += 1
    elif x == 50:
        n1 += 1
    elif x > 50:
        n2 += 1

ans = 0
if n2 > 0:
    ans = 1 << (n0 + n2 - 1)
    ans %= mod
print(ans)