var GET=(function(){function f(s){return new g(s);}function g(s){this._s=s.trim().split("\n");this._y=0;}g.prototype.a=function(f){var s=this._s, y=this._y, r;if(typeof s[y]==="string")s[y]=s[y].split(" ").reverse();r=s[y].pop();if(!s[y].length)this._y++;return f?r:+r;};g.prototype.l=function(f){var s=this._s[this._y++].split(" ");return f?s:s.map(a=>+a);};g.prototype.m=function(n,f){var r=this._s.slice(this._y,this._y+=n).map(a=>a.split(" "));return f?r:r.map(a=>a.map(a=>+a));};g.prototype.r=function(n,f){var r=this._s.slice(this._y,this._y+=n);return f?r:r.map(a=>+a);};return f;})();
var o=GET(require("fs").readFileSync("/dev/stdin","utf8"));

console.log(main());
function main(){
  var n = o.a();
  var k = o.a();
  var h = o.l();
  if(n <= k + 1)return Math.abs(h[n-1] - h[0]);
  var dp = [0];
  for(var i = 1; i <= k; i++)dp[i] = Math.abs(h[i] - h[0]);
  for(i = k+1; i < n; i++){
    var t = 9e99;
    for(var j = 1; j <= k; j++){
      var t2 = dp[i-j] + Math.abs(h[i] - h[i-j]);
      if(t > t2)t = t2;
    }
    dp[i] = t;
  }
  return dp[n-1];
}