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

def stepcmb(st):
    memo = [0]*(st+1)
    memo[0] = 1
    def _fib(st):
        if st <= 1:
            return 1
        if memo[st] != 0:
            return memo[st]
        memo[st] = _fib(st-1) + _fib(st-2)
        return memo[st]
    return _fib(st)

if m >= 2:
    for i in range(1, m):
        if steps[i] - steps[i-1] == 1:
            print(0)
            exit()

res = 1
nowstep = 0
for i in range(m):
    res *= stepcmb(steps[i]-nowstep-1) % (10**9+7)
    nowstep = steps[i] + 1
res = (res * stepcmb(n-nowstep)) % (10**9+7)

print(res)