import java.util.*;

public class Main {
   public static void main(String[] args) throws Exception {
       Scanner koko = new Scanner(System.in);
       int n = koko.nextInt();
       long k = koko.nextInt();
       String s = koko.next();
       int had=0;
       int[] paid = new int[n];
       int atari=0;
       paid[0]=1;
       if(s.charAt(0)=='1'){
           atari=1;
       }else if(s.charAt(0)=='2'){
           atari=2;
       }
       for(int i=1; i<n; i++){
           paid[i]=paid[i-1]+1;
           if(atari>0){
               paid[i]--;
               atari--;
           }
           if(s.charAt(i)=='1'){
               atari++;
           }else if(s.charAt(i)=='2'){
               atari+=2;
           }
       }
       if(n>=k){
           System.out.println(paid[(int)k-1]);
       }else{
           if(atari>=paid[n-1]){
               System.out.println(paid[n-1]);
           }else if(atari==0){
               int amari = (int)k%n;
               int ama=0;
               if(amari!=0){
                   ama=paid[amari-1];
               }
               long rpay = (paid[n-1]*(k-amari)/n)+ama;
               System.out.println(rpay);
           }else{
               int amari=(int)k%n;
               int ama=0;
               if(amari!=0&&atari<=paid[amari-1]){
                   ama=paid[amari-1]-atari;
               }
               long rpay = ama+atari+((paid[n-1]-atari)*(k-amari)/n);
               System.out.println(rpay);
           }
       }
   }       
}