n, m = map(int, input().split())

s = [0] * (n + 1)
s[-1] = 1
for _ in range(m):
    a = int(input())
    s[a] = None

if s[0] is None and s[1] is None:
    print(0)
    exit()

for i in range(n - 1, -1, -1):
    if s[i] is None:
        continue
    if i + 1 < len(s) and s[i + 1] is not None:
        s[i] += s[i + 1]
    if i + 2 < len(s) and s[i + 2] is not None:
        s[i] += s[i + 2]

print(s[0] % 1_000_000_007)
