n,m=map(int,input().split())
stair_m=[True]*(110000)
for i in range(m):
    a=int(input())
    stair_m[a]=False
dp=[0]*(110000)
dp[0]=1
for i in range(2,n+2):
    #print(i,i-2,dp[i-2])
    if stair_m[i]:
        dp[i]=dp[i-1]+dp[i-2]
    else:
        dp[i]=0
print(dp[n]%1000000007)