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

arr = [0] * (n+1)
arr[0] = 1
for i in range(1, n+1):
    if i in a:
        arr[i] = 0
    else:
        arr[i] = (arr[i-1] + arr[i-2]) % 1000000007

print(arr[-1])
