import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.io.DataInputStream;
import java.util.Arrays;
import java.io.IOException;
import java.io.FileInputStream;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Reader in = new Reader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        BFrog2 solver = new BFrog2();
        solver.solve(1, in, out);
        out.close();
    }

    static class BFrog2 {
        public void solve(int testNumber, Reader in, PrintWriter out) {
            int n = in.nextInt();
            int k = in.nextInt();
            int[] a = new int[n];
            int[] dp = new int[n];
            Arrays.fill(dp, Integer.MAX_VALUE);
            for (int i = 0; i < n; ++i) {
                a[i] = in.nextInt();
            }
            dp[0] = 0;
            dp[1] = Math.abs(a[1] - a[0]);
            for (int i = 2; i < n; ++i) {
                for (int j = 1; j <= k; ++j) {
                    if (i - j >= 0) {
                        int x = Math.abs(a[i] - a[i - j]) + dp[i - j];
                        dp[i] = Math.min(dp[i], x);
                    }
                }
            }
            out.println(dp[n - 1]);
        }

    }

    static class Reader {
        final private int BUFFER_SIZE = 1 << 16;
        private DataInputStream din;
        private byte[] buffer;
        private int bufferPointer;
        private int bytesRead;

        public Reader(InputStream in) {
            din = new DataInputStream(in);
            buffer = new byte[BUFFER_SIZE];
            bufferPointer = bytesRead = 0;
        }

        public Reader(String file_name) {
            try {
                din = new DataInputStream(new FileInputStream(file_name));
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
            buffer = new byte[BUFFER_SIZE];
            bufferPointer = bytesRead = 0;
        }

        public int nextInt() {
            int ret = 0;
            byte c = read();
            while (c <= ' ') {
                c = read();
            }
            boolean neg = (c == '-');
            if (neg) {
                c = read();
            }
            do {
                ret = ret * 10 + c - '0';
            } while ((c = read()) >= '0' && c <= '9');

            if (neg) {
                return -ret;
            }
            return ret;
        }

        private void fillBuffer() {
            try {
                bytesRead = din.read(buffer, bufferPointer = 0, BUFFER_SIZE);
                if (bytesRead == -1) {
                    buffer[0] = -1;
                }
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }

        private byte read() {
            if (bufferPointer == bytesRead) {
                fillBuffer();
            }
            return buffer[bufferPointer++];
        }

    }
}



Measured memory_bytes: 23252