INFTY = 10**9+7
N,M = map(int,input().split())
A = []
for _ in range(M):
    A.append(int(input()))
dp = [0 for _ in range(N+1)]
dp[0] = 1
dp[1] = 1
cur = 0
if A[0]==1:
    dp[1] = 0
    cur = 1
for i in range(2,N+1):
    if cur<M and i==A[cur]:
        cur += 1
    else:
        dp[i] = (dp[i-1]+dp[i-2])%INFTY
print(dp[N])