n,m=map(int,input().split())
b=[int(input()) for _ in range(m)]
a=[]
if 1 not in b:
  a.append(1)
else:a.append(0)
if 2 not in b:
  a.append(2)
else:a.append(0)
for i in range(2,n):
  if i+1 not in b:
    a.append((a[-1]+a[-2])%(10**9+7))
  else:a.append(0)
print(a[-1])