N,M = map(int,input().split())
br = []
dp = [0]*(N+1)
for i in range(M):
    a = int(input())
    br.append(a)

dp[0] = 1

if 1 in br:
    dp[1] = 0
else:
    dp[1] = 1

for i in range(2,N+1):
    if i in br:
        dp[i] = 0
    else:
        dp[i] = dp[i-1] + dp[i-2]

print(dp[N] % (10**9+7))