N, M = map(int, input().split())
a = [int(input()) for _ in range(M)]
dp = [0 for _ in range(N+1)]
MOD = int(1e9) + 7
dp[0] = 1
# DP
if 1 not in a:
    dp[1] = 1
for i in range(2, N+1):
    if i in a:
        continue
    dp[i] = (dp[i-2] + dp[i-1]) % MOD
print(dp[-1])