n, m = map(int, input().split())
a_l = [ int(input()) for _ in range(m) ]

dp = [0] * (n+1)
dp[0] = 1
if 1 not in a_l:
    dp[1] = 1
else:
    dp[1] = 0
if 2 not in a_l:
    dp[2] = dp[0] + dp[1]
else:
    dp[2] = 0
for i in range(2,n+1):
    if i not in a_l:
        dp[i] = dp[i-1] + dp[i-2]
    else:
        dp[i] = 0
print(dp[-1]%1000000007)