n, m = map(int, input().split())
a = list(int(input()) for _ in range(m))

for i in range(m):
    if m == 1:
        break
    if a[i+1] - a[i] == 1:
        print(0)
        exit()

dp = [0] * (n+1)
dp[0] = 1

if 1 in a:
    dp[1] = 0
else:
    dp[1] = 1

for i in range(2, n+1):
    if i in a:
        continue
    dp[i] = dp[i-1] + dp[i - 2]
    dp[i] %= 1000000007

print(dp[n])
