N,M = map(int, input().split())
a = [int(input()) for _ in range(M)]
dp = [0 for _ in range(N+1)]
dp[0] = 1
for i in range(N+1):
    if i in a:
        continue
    else:
        if i+1 not in a and i+1 <= N:
            dp[i+1] += dp[i]
        if i+2 not in a and i+2 <= N:
            dp[i+2] += dp[i]
print(dp[-1]%1000000007)