N,M = map(int,input().split())
a = [int(input()) for _ in range(M)]
booli = [False]*(N)
for i in a:
    booli[i-1] = True
mod = 1000000007
INF = -1
dp = [INF]*(N+1)
dp[0] = 1
if booli[1]:
    dp[1] = 0
else:
    dp[1] = 1
def solve():
    for i in range(2,N+1):
        if booli[i-1]:
            dp[i] = 0
        else:
            dp[i] = dp[i-1]+dp[i-2]
    return dp[N]%mod
print(solve())