#include <bits/stdc++.h>
#define F first
#define S second
//#define mp make_pair
#define pb push_back

using namespace std;
typedef long long ll;

const int MOD = 998244353;
const int N = 5e3 + 9;
const int M = 1e6 + 9;
const int INF = 2e9 + 5;
const int K = 100 + 9;

ll nCr[N][N], res, ones[N];

ll Flex (ll x) {
    return ((x % MOD) + MOD) % MOD;
}

ll calc (int l, int r) {
    return nCr[r - l + 1][ones[r] - ones[l - 1]];
}

int main () {
    int n, k;
    cin >> n >> k;

    string s;
    cin >> s;
    s = "3" + s;

    nCr[1][0] = nCr[1][1] = 1;
    for (int i = 2; i < N; i++) {
        nCr[i][0] = 1;
        for (int j = 1; j <= i; j++)
            nCr[i][j] = Flex (nCr[i - 1][j] + nCr[i - 1][j - 1]);
    }

    if (k == 0) {
        puts ("1");

        return 0;
    }

    for (int i = 1; i <= n; i++)
        ones[i] = ones[i - 1] + (s[i] == '1');

    if (ones[n] < k) {
        puts ("1");

        return 0;
    }

    int last = -1;
    for (int i = 1; i <= n; i++) {
        int newLast = i, cnt = 0;
        for (; newLast <= n; newLast++) {
            cnt += (s[newLast] == '1');

            if (cnt == k && newLast == n)
                break;

            if (cnt == k && s[newLast + 1] == '1')
                break;
        }

        if (newLast > n)
            break;
        res = Flex (res + calc (i, newLast));

        if (last == -1) {
            newLast = last;

            continue;
        }

        res = Flex (res - calc(i, last));
        last = newLast;
    }

    cout << res << "\n";

    return 0;
}