import java.util.ArrayList;
import java.util.HashSet;
import java.util.Scanner;


public class Main {
	static int N, K;
	static String S;
			
	static private void solve()
	{
		// 一周分測定する
		int buybar = 0;
		int nextbar = 0;
		int freebar = 0;
		
		for (int k = 0; k < N; k++) {
			if (freebar > 0) 
				freebar--;
			else 
				buybar++;
			
			switch (S.charAt(k)) {
			case '0': break;
			case '1': freebar++;  break;
			case '2': freebar+=2; break;
			}
			
			if((k+1) == K)
			{
				System.out.println(buybar);
				return;
			}
		}
		
		// 一周するときに
		int loopbuy = buybar;
		int loopfree = freebar;
		
		if(loopbuy <= loopfree)
		{
			System.out.println(loopbuy);
			return;
		}
		
		buybar = 0;
		nextbar = 0;
		freebar = 0;
		
		int loop = K/N;
		
		int k = loop * N;
		freebar = loopfree;
		buybar = loopbuy + (loopbuy - loopfree) * (loop - 1);
		
		/*for (int i = 0; i < loop; i++) {
			if(freebar >= loopbuy)
			{
				freebar -= loopbuy;
			}
			else {
				buybar += loopbuy - freebar;
				freebar = 0;
			}
			
			freebar += loopfree;
		}*/
		for (; k < K; k++) {
			if (freebar > 0) 
				freebar--;
			else 
				buybar++;
			
			switch (S.charAt(k%N)) {
			case '0': break;
			case '1': freebar++;  break;
			case '2': freebar+=2; break;
			}
		}
		
		System.out.println(buybar);
	}
	
	static public void main(String[] args)
	{
		Scanner sca = new Scanner(System.in);
		
		N = sca.nextInt();
		K = sca.nextInt();
		S = sca.next();
		
		solve();
	}
}