mod=1000000007
n,m=map(int,input().split())
a=[]
af=0
for i in range(m):
    a.append(int(input()))
al=len(a)
if al>0:
    a.sort()
    af=1
f=0
for i in range(len(a)):
    if a[i]+1 in a:
        f=1
        break
if f==1:
    print(0)
else:
    dp=[0]*(n+1)
    dp[0]=1
    if 1 in a:
        dp[1]=0
        a.pop(0)
        al-=1
    else:
        dp[1]=1
    
    for i in range(2,n+1):
        if al>0 and i==a[0]:
            dp[i]=0
            a.pop(0)
            al-=1
        else:
            dp[i]=(dp[i-1]+dp[i-2])%mod
    print(dp[n]%mod)
  