INF = 1i64 << 60
n, k = read_line.split.map(&.to_i)
a = read_line.split.map(&.to_i64)
dp = Array.new(2) { Array.new(k + 1, -INF) }
dp[0][0] = 0
n.times do |i|
  (k - 1).downto(0) do |j|
    dp[1][j + 1] = {dp[1][j + 1], dp[0][j] + a[i]}.max if dp[0][j] != -INF
    dp[0][j] = {dp[0][j], dp[1][j]}.max if dp[1][j] != -INF
  end
end
ans = {dp[0][-1], dp[1][-1]}.max
puts ans == -INF ? "Impossible" : ans