n,m = map(int, input().split())
a = [int(input()) for _ in range(m)]
p = [0]*(n+1)
p[0] = 1
if 1 not in a:
  p[1] = 1

t = 1000000007

for i in range(2, n+1):
  if i in a:
    continue
  s = p[i-1] + p[i-2]
  s = s%t
  p[i] = s
  
print(p[n])  
  
