// yukicoder: No.78 クジ付きアイスバー
// 2019.6.22 bal4u

#include <stdio.h>

#if 1
#define gc() getchar_unlocked()
#else
#define gc() getchar()
#endif

int in() {   // 非負整数の入力
	int n = 0, c = gc();
	do n = 10 * n + (c & 0xf); while ((c = gc()) >= '0');
	return n;
}

void ins(char *s)  // 文字列の入力　スペース以下の文字で入力終了
{
	do *s = gc();
	while (*s++ > ' ');
	*(s-1) = 0;
}

int N, K;
char s[55];
int buy, atari;

void calc(int lim) {
	int i = 0;
	char *p = s;
	
	while (i < lim && *p) {
		if (atari) atari--;
		else buy++;
		i++;
		atari += *p++ & 0xf;
	}
}

int main()
{
	int i, n;
	char *p;
	
	N = in(), K = in(), ins(s);
	buy = atari = 0;
	if (K >= N) {
		calc(N);
		if (atari >= buy) {
			printf("%d\n", buy);
			return 0;
		}
		K -= N;
	}
	buy += (buy-atari)*(K/N);
	calc(K % N);
	printf("%d\n", buy);
	return 0;
}