n, m = map(int, input().split())
A = set()
for i in range(m):
    a.append(int(input()))
    A.add(a)
dp = [0] * (n + 1)
for i in range(n + 1):
    if i in a:
        dp[i] = 0
    else:
        if i == 0:
            dp[i] = 1
        elif i == 1:
            dp[i] = 1
        else:
            dp[i] = (dp[i - 1] + dp[i - 2]) % 1000000007
print(dp[n])

"""
100 5
1
23
45
67
89
"""