from collections import deque

N, M = map(int, input().split())

a = deque()
for _ in range(M):
    a.append(int(input()))

before1 = 1
before2 = 0
ai = a.popleft()
for i in range(N):
    if i == (ai-1):
        before2 = before1
        before1 = 0
        if len(a)>0:
            ai = a.popleft()
    else:
        current = divmod(before1 + before2, 10**9+7)[1]
        before2 = before1
        before1 = current
    
print(before1)
