#include <bits/stdc++.h>

using namespace std;

typedef long long int ll;
typedef double ld;

typedef pair<ll, ll> ii;
typedef vector<ll> vi;
typedef vector<ii> vii;

#define PB push_back
#define ff first
#define ss second

#define FOR(prom,a,b) for ( ll prom = (a); prom < (ll)(b); ++prom)
#define F(a) FOR(i,0,a)
#define FF(a) FOR(j,0,a)

//#define M_PI 3.14159265358979323846
#define EPS (1e-10)
#define EQ(a,b) (fabs(a-b) <= fabs(a+b)*EPS)
#define LINF (1<<62LL)
#define DEB cerr<<"DEB: "

#define MX 1000
#define MOD 1000000007

ll N, K; 
string in;

ll DP[4][MX+1][MX+1];

int main() {
	ios::sync_with_stdio(false);

	cin >> N >> K;
	
	memset(DP,0,4*(MX+1)*(MX+1)*sizeof(ll));
	
	string in;
	cin >> in;
	
	if ( in[N-1] == '1' ) {
		DP[1][N-1][1] = 1;
		DP[2][N-1][0] = 1;
	} else {
		DP[0][N-1][0] = 1;
		DP[1][N-1][1] = 1;
	}
	
	for ( ll po = N-2; po >= 0; --po) {
		for ( ll su = 0; su <= K; ++su) {
			if ( in[po] == '1') {
				DP[0][po][su] = 0;
				DP[1][po][su+1] = DP[0][po+1][su] + DP[1][po+1][su];
				DP[2][po][su] = DP[0][po+1][su] + 
								DP[1][po+1][su] + 
								DP[2][po+1][su] + 
								DP[3][po+1][su];
				DP[3][po][su+1] = DP[2][po+1][su] + DP[3][po+1][su];
			} else {
				DP[0][po][su] = DP[0][po+1][su] + DP[1][po+1][su];
				DP[1][po][su+1] = DP[0][po+1][su] + 
								DP[1][po+1][su] + 
								DP[2][po+1][su] + 
								DP[3][po+1][su];
				DP[2][po][su] = DP[2][po+1][su] + DP[3][po+1][su];
				DP[3][po][su+1] = 0;
			}
		}
	}
	
	cout << DP[2][0][K-1] + DP[3][0][K-1] + DP[0][0][K] + DP[1][0][K] << endl;

	return 0;

}