from functools import lru_cache

n, m = [int(i) for i in input().split()]

@lru_cache(maxsize=10000)
def countPattern(s, cnt):
    if s > 1:
        cnt = countPattern(s-2, cnt)
        cnt = countPattern(s-1, cnt)
        return cnt
    else:
        return cnt + 1


ans = 1
a_pre = -1
for mi in range(m):
    a = int(input())
    if a == a_pre:
        break
    elif a == a_pre + 1:
        ans = 0
    ans = ans * countPattern(a-a_pre-2, 0) % 1000000007
    a_pre = a

a = n + 1
ans = ans * countPattern(a - a_pre - 2, 0) % 1000000007

print(ans)

# TLE