#include <bits/stdc++.h>
using namespace std;
void judge() {}
const int MOD = 998244353;
int add(int x, int y) {
  x += y;
  while (x >= MOD) x -= MOD;
  while (x < 0) x += MOD;
  return x;
}
int main() {
  judge();
  int n;
  cin >> n;
  int k;
  cin >> k;
  string s;
  cin >> s;
  vector<int> p(n + 1);
  for (int i = 0; i < n; i++) p[i + 1] = p[i] + (s[i] - '0');
  vector<vector<int>> C(n + 1);
  for (int i = 0; i <= n; i++) {
    C[i].resize(i + 1);
    C[i][0] = C[i][i] = 1;
    for (int j = 1; j < i; j++) C[i][j] = add(C[i - 1][j], C[i - 1][j - 1]);
  }
  int ans = 1;
  for (int i = 0; i < n; i++)
    for (int j = i + 1; j < n; j++) {
      int cnt = j + 1 - i;
      int cnt1 = p[j + 1] - p[i];
      if (cnt1 > k || p[n] < k) continue;
      cnt -= 2;
      if (s[i] == '0') cnt1--;
      if (s[j] == '0') cnt1--;
      if (cnt1 <= cnt && cnt1 >= 0 && cnt >= 0) ans = add(ans, C[cnt][cnt1]);
    }
  cout << ans << endl;
  return 0;
}
