#3問目
NM = input().split()
N,M = int(NM[0]), int(NM[1])
A = []
dp = [0] * (N+1)
dp[0] = 1
dp[1] = 1
MOD = 1000000007
for _ in range(M):
    A.append(int(input()))
    
if(1 in A):
    dp[1] = 0

for i in range(2, N+1):
    #貰うdp
    if(i in A):
        dp[i] = 0
    else:
        dp[i] = dp[i-1] + dp[i-2]
    dp[i] %=MOD
    
print(dp[N])