lis = [1,1,2]
def num(n):
    if len(lis) >= n+1:
        return lis[n]
    else:
        res = num(n-2) + num(n-1)
        lis.append(res)
        return res

N,M = map(int,input().split())
count = 1
pre = 0
for i in range(M+1):
    if i == M:
        cur = N+1
    else:
        cur = int(input())
    number = cur-1-pre
    if number >= 0:
        count = count * num(number) % 1000000007
    else:
        count = 0
        break
    pre = cur + 1
print(count%1000000007)    