N, M = map(int, input().split())

A = []
for i in range(M):
  A.append(int(input()))

A.sort()
ida = 0
a = A[ida]
mod = 10**9 + 7

x = [1] + [0]*N
if a == 1:
  ida += 1
  if M >= 2:
    a = A[ida]
  else:
    x[1] = 1

for i in range(2, N+1):
  if i == a:
    ida += 1
    if ida >= M:
      a = N+1
    else:
      a = A[ida]
  
    x[i] = 0
  else:
    x[i] = (x[i-1] + x[i-2]) % mod

print(x[N])