MOD = 1_000_000_007
N, M = gets.split.map(&:to_i)
dp = Array.new(N + 10, 0)
dp[0] = 1
M.times.map{gets.to_i}.each do |h|
  dp[h] = -1
end
(1 .. N).each do |h|
  dp[h] = dp[h] < 0 ? 0 : (dp[h-1] + dp[h-2]) % MOD
end
puts dp[N]
