n,m=map(int,input().split())
mod=10**9+7
a = [int(input()) for i in range(m)]
block=[0,1]
x=[True for i in n]
for j in a:
  x[j-1]=False

for i in range(1,n+1):
  if x[i-1]==True:
    block=block[1:]+[0]
  else:
    block=block[1:]+[sum(block)%mod]
print(block[-1])
