N, M = map(int, input().split())
A = [int(input()) for _ in range(M)]

B = [-1] + A + [N + 1]
B = [B[i + 1] - B[i] - 2 for i in range(M + 1)]

total = max(B)
dp = [0] * (total + 1)
dp[0] = 1
dp[1] = 1

for i in range(total - 1):
    dp[i + 2] = (dp[i + 1] + dp[i]) % (10 ** 9 + 7)
        
ans = 1
for i in range(M + 1):
    ans *= dp[B[i]]
    ans %= 10 ** 9 + 7
print(ans if -1 not in B[1:] else 0)