import sys
input=sys.stdin.readline
n,m=map(int,input().split())
if m>0:
    a=[int(input()) for i in range(m)]

dp=[0]*(n+1)
dp[0]=1
if m>0:
    if a[0]==1:
        dp[1]=0
    else:
        dp[1]=1
else:
    dp[1]=1

for i in range(2,n+1):
    if m>0:
        if i in a:
            dp[i]=0
        else:
            dp[i]=(dp[i-2]+dp[i-1])%1000000007
    
    else:
        dp[i]=(dp[i-2]+dp[i-1])%1000000007

print(dp[-1])