n,m=map(int,input().split())
a=list(int(input()) for _ in range(m))
mod=10**9+7
pattern=[0]*(n+1)
pattern[0]=pattern[1]=1
if 1 in a:
    pattern[1]=0
for i in range(2,n+1):
    if i in a:
        pattern[i]=0
    else:
        pattern[i]=(pattern[i-1]+pattern[i-2])%mod
print(pattern[n]%mod)