n, m = map(int, input().split(' '))
if m > 0:
    aaa = set(map(int, sys.stdin))
else:
    aaa = set()

dp = [0] * (n+1)
dp[0] = 1
dp[1] = 1 if 1 not in aaa else 0

mod=10**9+7
for i in range(2, n+1):
    if i in aaa:
        continue
    dp[i] = (dp[i-1]+dp[i-2])%mod

print(dp[n])