n,*a = map(int,open(0).read().split())
MOD = 10**9+7
ans = 0
nxt = [0,1,1,1,0,1,1,0]
for x in range(4):
    dp = [0]*4
    dp[x] = 1
    for i in range(1,n-1):
        ndp = [0]*4
        for j in range(4):
            for k in range(2):
                if a[i] == nxt[j*2+k]:
                    nj = (j*2+k)%4
                    ndp[nj] += dp[j]
                    ndp[nj] %= MOD
        dp = ndp    
    for y in range(4):
        if nxt[y%2*4+x] == a[0] and nxt[y*2+x//2] == a[n-1]:
            ans += dp[y]
print(ans%MOD)