MOD = 10**9+7
n, m = map(int, input().split())
dp = [0] * (n+1)
dp[0] = 1

# skip用 list
A = [0] * (n+1) 
for _ in range(m):
  broken = int(input())
  A[broken] = 1

# dp
for i in range(1, n+1):
  if A[i] == 1:
    dp[i] = 0
  else:
    dp[i] = (dp[i-1] + dp[i-2]) % MOD
    
print(dp[n])