import sys
n,m=map(int,input().split())
a=list(map(int,sys.stdin))
dp=[0]*(n+1)
dp[0]=1
if 1 not in a:dp[1]=1
for i in range(2,n+1):
    if i in a:continue
    if dp[i-1]==dp[i-2]==0:break
    dp[i]=(dp[i-1]+dp[i-2])%1000000007
print(dp[-1])