N,M = map(int,input().split())
a = []
for i in range(M):
    a.append(int(input()))
dp = [0]*(N+1)
dp[1] = 1
if 1 in a:
    dp[2] = 1
    dp[1] = 0
else:
    dp[2] = 2
for i in range(3,N+1):
    if i-1 in a:
        dp[i] = dp[i-2]
        dp[i-1] = 0
    else:
        dp[i] = dp[i-2]+dp[i-1]
ans = dp[N]%1000000007
print(ans)
