var obj = init(); Main(); function nextInt(){return myconv(next(),1);} function nextStrArray(){return myconv(next(),2);}//半角スペース分割 function nextIntArray(){return myconv(next(),4);}//半角スペース + 数値化 function nextCharArray(){return myconv(next(),6);}//1文字分割 function next(){return obj.next();} function hasNext(){return obj.hasNext();} function myin(){return require("fs").readFileSync("/dev/stdin", "utf8").trim().split("\n");} function init(){ var inputFile = myin(); var returnObj = { "list" : inputFile, "index" : 0, "max" : inputFile.length, "hasNext" : function(){return (this.index < this.max);}, "next" : function(){if(!this.hasNext()){throw "ArrayIndexOutOfBoundsException これ以上ないよ";}else{var returnInput = this.list[this.index];this.index++;return returnInput;}} }; return returnObj; } function myout(t){console.log(t);}//標準出力 function myerr(t){console.error(t);}//標準エラー出力 //[no]要素の扱い。数値型 //不明値、異常時:引数そのまま返す 1:数値へ変換 //2:半角SPで分割 4:半角SPで分割し、数値配列へ //6:1文字で分割 7:1文字で分割し、数値配列へ //8:半角SPで結合 9:改行で結合 0:文字なしで結合 function myconv(i,no){try{switch(no){case 1:return parseInt(i);case 2:return i.split(" ");case 4:return i.split(" ").map((a)=>Number(a));case 6:return i.split("");case 7:return i.split("").map((a)=>Number(a));case 8:return i.join(" ");case 9:return i.join("\n");case 0:return i.join("");default:return i;}}catch(e){return i;}} function Main(){ var one = nextIntArray(); var L = one[0]; var K = one[1]; var count = Math.floor(L / (2 * K)); if(L == 2 * K){ count--; } myout(count * K); }