n,m = map(int, input())
a = set()
for i in range(m):
  a.add(int(input()))
  
b = [0]* (n+1)
b[0] = 1
if 1 not in a:
  b[1] = 1
for i in range(2, n+1):
  if i in a:
    b[i] = 0
  else:
    b[i] = b[i-1] + b[i-2]
print(b[n] % 1000000007)