function myin(){return require("fs").readFileSync("/dev/stdin", "utf8").trim();}
function myout(t){console.log(t);}//standard output
function myerr(t){console.error(t);}//standard error
//[no]param
//0:何もしない  1:数値へ変換  2:半角SPで分割  3:改行で分割  4:半角SPで分割し、数値配列へ
//5:改行で分割し、数値配列へ  6:1文字に分割  7:1文字に分割し、数値配列へ
function myconv(i,no){switch(no){case 0:return i;case 1:return parseInt(i);case 2:return i.split(" ");case 3:return i.split("\n");case 4:return i.split(" ").map((a)=>Number(a));case 5:return i.split("\n").map((a)=>Number(a));case 6:return i.split("");case 7:return i.split("").map((a)=>Number(a));}}
function Main(input) {
  input = myconv(input,3);
  var N = myconv(input[0],4)[0];
  var K = myconv(input[0],4)[1];
  var R = myconv(input[1],4)[0];
  var S = myconv(input[1],4)[1];
  var P = myconv(input[1],4)[2];
  var output = 0;
  var list = myconv(input[2],6);
  var jibun = [];
  for(var i = 0; i < N; i++){
    switch(list[i]){
      case "r":
        if(i < K){
           output += P;
          jibun.push("p");
        }else{
          if(jibun[i-K] != "p"){
             output += P;
          	jibun.push("p");
          }else{
            jibun.push("x");
          }
        }
        break;
      case "s":
        if(i < K){
           output += R;
          jibun.push("r");
        }else{
          if(jibun[i-K] != "r"){
             output += R;
          	jibun.push("r");
          }else{
            jibun.push("x");
          }
        }
        break;
      case "p":
        if(i < K){
           output += S;
          jibun.push("s");
        }else{
          if(jibun[i-K] != "s"){
             output += S;
          	jibun.push("s");
          }else{
            jibun.push("x");
          }
        }
        break;
	}
  }
  //myout(jibun);
  myout(output);
}
Main(myin());