import sys
sys.setrecursionlimit(10 ** 7)

read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines

N,M = map(int,readline().split())
A = [True] * (N+10)
MOD = 10 ** 9 + 7
for _ in range(M):
  x = int(readline())
  A[x] = False


DP = [0] * (N+1)
DP[0] = 1

for i in range(N):
  if not A[i]:
    continue
  
  if A[i+1]:
    DP[i+1] += DP[i]
    DP[i+1] %= MOD
  if A[i+2]:
    DP[i+2] += DP[i]
    DP[i+2]: %= MOD
       
print(DP[N]%MOD)
      
  


