There are N squares aligned in a row. The i-th square from the left contains an integer a_i.

Initially, all the squares are white. Snuke will perform the following operation some number of times:

* Select K consecutive squares. Then, paint all of them white, or paint all of them black. Here, the colors of the squares are overwritten.



After Snuke finishes performing the operation, the score will be calculated as the sum of the integers contained in the black squares. Find the maximum possible score.

Constraints

* 1≤N≤10^5
* 1≤K≤N
* a_i is an integer.
* |a_i|≤10^9

Input

The input is given from Standard Input in the following format:


N K
a_1 a_2 ... a_N


Output

Print the maximum possible score.

Examples

Input

5 3
-10 10 -10 10 -10


Output

10


Input

4 2
10 -10 -10 10


Output

20


Input

1 1
-10


Output

0


Input

10 5
5 -4 -5 -8 -4 7 2 -4 0 7


Output

17
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.List;
import java.util.NoSuchElementException;


public class Main {
  public static void main(String[] args) {
    FastScanner sc = new FastScanner();
    int N = sc.nextInt();
    int K = sc.nextInt();

    BIT bit = new BIT(N);
    long[] a = new long[N + 1];
    long ret = 0;
    for (int i = 1; i <= N; i++) {
      a[i] = sc.nextLong();
      bit.add(i, a[i]);

      if (a[i] >= 0) {
        ret += a[i];
      }
    }

    long max1 = Long.MIN_VALUE;
    long max2 = Long.MIN_VALUE;

    List<Integer> idx1 = new ArrayList<>();
    List<Integer> idx2 = new ArrayList<>();
    for (int i = 1; i <= N - K + 1; i++) {
      long now = bit.sum(i, i + K - 1);

      if (max1 < now) {
        max1 = now;
        idx1 = new ArrayList<>();
        idx1.add(i);
      } else if (max1 == now) {
        idx1.add(i);
      }

      if (max2 < -now) {
        max2 = -now;
        idx2 = new ArrayList<>();
        idx2.add(i);
      } else if (max2 == -now) {
        idx2.add(i);
      }
    }

    long A = Long.MIN_VALUE;
    for (int idx : idx1) {
      long ret1 = ret;
      for (int i = idx; i < idx + K; i++) {
        if (a[i] < 0) {
          ret1 += a[i];
        }
      }
      A = Math.max(A, ret1);
    }

    for (int idx : idx2) {
      long ret1 = ret;
      for (int i = idx; i < idx + K; i++) {
        if (a[i] > 0) {
          ret1 -= a[i];
        }
      }
      A = Math.max(A, ret1);
    }
   System.out.println(A);
  }


}


class BIT {
  private long[] array;
  private int n;

  public BIT(int n) {
    this.array = new long[n + 1];
    this.n = n;
  }

  public void add(int a, long w) {
    for (int i = a; i <= n; i += (i & -i)) {
      array[i] += w;
    }
  }

  public long sum(int a) {
    long ret = 0;
    for (int i = a; i > 0; i -= (i & -i)) {
      ret += array[i];
    }
    return ret;
  }

  public long sum(int a, int b) {
    return a == 0 ? sum(b) : (sum(b) - sum(a - 1));
  }

}


class FastScanner {
  public static String debug = null;

  private final InputStream in = System.in;
  private int ptr = 0;
  private int buflen = 0;
  private byte[] buffer = new byte[1024];
  private boolean eos = false;

  private boolean hasNextByte() {
    if (ptr < buflen) {
      return true;
    } else {
      ptr = 0;
      try {
        if (debug != null) {
          buflen = debug.length();
          buffer = debug.getBytes();
          debug = "";
          eos = true;
        } else {
          buflen = in.read(buffer);
        }
      } catch (IOException e) {
        e.printStackTrace();
      }
      if (buflen < 0) {
        eos = true;
        return false;
      } else if (buflen == 0) {
        return false;
      }
    }
    return true;
  }

  private int readByte() {
    if (hasNextByte())
      return buffer[ptr++];
    else
      return -1;
  }

  private static boolean isPrintableChar(int c) {
    return 33 <= c && c <= 126;
  }

  private void skipUnprintable() {
    while (hasNextByte() && !isPrintableChar(buffer[ptr]))
      ptr++;
  }

  public boolean isEOS() {
    return this.eos;
  }

  public boolean hasNext() {
    skipUnprintable();
    return hasNextByte();
  }

  public String next() {
    if (!hasNext())
      throw new NoSuchElementException();
    StringBuilder sb = new StringBuilder();
    int b = readByte();
    while (isPrintableChar(b)) {
      sb.appendCodePoint(b);
      b = readByte();
    }
    return sb.toString();
  }

  public long nextLong() {
    if (!hasNext())
      throw new NoSuchElementException();
    long n = 0;
    boolean minus = false;
    int b = readByte();
    if (b == '-') {
      minus = true;
      b = readByte();
    }
    if (b < '0' || '9' < b) {
      throw new NumberFormatException();
    }
    while (true) {
      if ('0' <= b && b <= '9') {
        n *= 10;
        n += b - '0';
      } else if (b == -1 || !isPrintableChar(b)) {
        return minus ? -n : n;
      } else {
        throw new NumberFormatException();
      }
      b = readByte();
    }
  }

  public int nextInt() {
    return (int) nextLong();
  }

  public long[] nextLongList(int n) {
    return nextLongTable(1, n)[0];
  }

  public int[] nextIntList(int n) {
    return nextIntTable(1, n)[0];
  }

  public long[][] nextLongTable(int n, int m) {
    long[][] ret = new long[n][m];
    for (int i = 0; i < n; i++) {
      for (int j = 0; j < m; j++) {
        ret[i][j] = nextLong();
      }
    }
    return ret;
  }

  public int[][] nextIntTable(int n, int m) {
    int[][] ret = new int[n][m];
    for (int i = 0; i < n; i++) {
      for (int j = 0; j < m; j++) {
        ret[i][j] = nextInt();
      }
    }
    return ret;
  }
}
