n,m=map(int,input().split())
a=[0]*(n+1)
b=[int(input()) for i in range(m)]
a[0]=a[1]=1
if m==0:
  for i in range(2,n+1):
    a[i]=(a[i-1]+a[i-2])%(10**9+7)
else:
  j=0
  if b[0]==1:
    if m!=1:
      j=1
  else:
    a[1]=1
  for i in range(2,n+1):
    if i==b[j]:
      if j<m-1:
        j+=1
    else:
      a[i]=(a[i-1]+a[i-2])%(10**9+7)
print(a[n])