n,m = map(int,input().split())
dp = [0]*(n+1)
for i in range(m):
    a = int(input())
    dp[a] = -1
dp[0] = 1
if dp[1] != -1:
    dp[1] = 1
for i in range(1,n+1):
    if dp[i] == -1:
        dp[i] = 0
    else:
        dp[i] = (dp[i-1]+dp[i-2])%1000000007
print(dp[n])