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

dp = [0] * (n+1)
dp[0] = 1
if (1 in a):
    dp[1] = 0
else:
    dp[1] = 1

for i in range(2,n+1):
    if (i in a):
        dp[i] = 0
    else:
        dp[i] = (dp[i-1] + dp[i-2])%(10**9+7)

print(dp[n])