N = int(input())
P = list(map(int,input().split()))
dp = [[0] * 2 for _ in range(N + 1)]
mod = 10 ** 9 + 7
dp[0][0] = 1

import sys
for p in P:
    if p == 50:
        print(pow(2,mod-2,mod))
        exit()
for i in range(1,N+1):
    if P[i-1] > 50:
        dp[i][1] = dp[i-1][0] + dp[i-1][1]
        dp[i][0] = dp[i-1][1] + dp[i-1][0]
    elif P[i-1] == 50:
        dp[i][0] = dp[i-1][0] * 2
        dp[i][1] = dp[i-1][1] * 2
    else:
        dp[i][1] = dp[i-1][1] * 2
        dp[i][0] = dp[i-1][0] * 2
    dp[i][0] %= mod
    dp[i][1] %= mod
print(dp[-1][1])