#include <bits/stdc++.h>
using namespace std;
using i64 = long long;
const int N = 5050, MOD = 998244353;
i64 inv[N], fac[N], inv_fac[N];
void precalc() {
  inv[1] = 1;
  for (int n = 2; n < N; n++) {
    inv[n] = (MOD - (MOD / n) * inv[MOD % n] % MOD) % MOD;
  }
  fac[0] = 1;
  for (int n = 1; n < N; n++) {
    fac[n] = n * fac[n - 1] % MOD;
  }
  inv_fac[0] = 1;
  for (int n = 1; n < N; n++) {
    inv_fac[n] = inv[n] * inv_fac[n - 1] % MOD;
  }
}
i64 binom(i64 n, i64 k) {
  if (k < 0 || k > n) return 0;
  return fac[n] * inv_fac[k] % MOD * inv_fac[n - k] % MOD;
}
int main() {
  int n, k;
  cin >> n >> k;
  precalc();
  string a;
  cin >> a;
  i64 res = 1;
  for (int i = 0; i < n; i++) {
    int o = 0, j = i;
    for (; j < n; j++) {
      if (o == k && a[j] == '1') break;
      o += a[j] == '1';
    }
    if (i == 0 && o < k) break;
    int z = j - i - o;
    res = (res + binom(j - i - 1, z - (a[i] == '1'))) % MOD;
    cerr << j - i - 1 << " " << z - (a[i] == '1') << endl;
  }
  cout << res << '\n';
}
