f=[1,1,1]
for i in range(3,100001):
 f.append((f[i-1]+f[i-3])%1000000007)

ans=1
start=0
a,b=input().split()
a=int(a)
b=int(b)
line=input().split()
for i in range(b):
 x=int(line[i])
 ans=(ans*f[x-start])%1000000007
 start=x
ans=(ans*f[a-start])%1000000007
print(ans)