N, M = [int(nm) for nm in input().split()]
if M != 0:
  a = int(input())
  M -= 1

C = [1, 0] # [-2段目, -1段目]
C += [0]*(N+10) # C = [-2段目, -1段目, 0段目, 1段目, 2段目, ...]
for n in range(0, N+1):
  if n != a or M == 0:
    C[n+2] = (C[n] + C[n+1]) % 1000000007
  else: # n == a and M != 0:
    C[n+2] = 0
    a = int(input())
    M -= 1

ans = C[N+2]  % 1000000007
print(ans)