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

dp = [0] * (n+1)
dp[0] = 1

for i in range( 1, n+1):
    if i in a:
        dp[i]= 0
    else:
        dp[i]= (dp[i-1] + dp[i-2])

print(dp[n] % 1000000007)