n, m = map(int, input().split())
a = [ int(input()) for _ in range(m) ]
dp = [0]*n
if not 1 in a:
  dp[0] = 1
if not 2 in a:
  dp[1] = 1 + dp[0]
for i in range(2, n):
  if i+1 in a:
    dp[i] = 0
  else:
    dp[i] = dp[i-2] + dp[i-1]
print(dp[n-1]%1000000007)