import sys
n, m = map(int, input().split())
a = [int(sys.stdin.readline()) for _ in range(m)]
mod = 1000000007
dp = [0] * (n + 1)
dp[0] = 1
dp[1] = dp[0] if not 1 in a else 0
for i in range(2, n + 1):
    if not i in a:
        dp[i] = (dp[i - 1] + dp[i - 2]) % mod
    else:
        dp[i]=  0
print(dp[n])
