#include <bits/stdc++.h>
// #define int long long
using namespace std;

#define _upgrade                  \
    ios_base::sync_with_stdio(0); \
    cin.tie(0);                   \
    cout.tie(0);
#define FOR(i, a, b) for (int i = a; i <= b; i++)
#define FORB(i, a, b) for (int i = a; i >= b; i--)
#define REP(i, a) for (int i = 0; i < a; i++)
#define REP1(i, a) for (int i = 1; i < a; i++)
#define REPB(i, a) for (int i = a - 1; i >= 0; i--)
#define TRAV(a,x) for (auto& a: x)
#define LINE "---------------------\n"
#define ALL(A) A.begin(), A.end()
#define LLA(A) A.rbegin(), A.rend()
#define Q queue
#define ff first
#define ss second
#define rs resize
#define ins insert 
#define fr front() 
#define ts to_string
#define pb push_back
#define mp make_pair
#define lb lower_bound 
#define ub upper_bound 
#define umap unordered_map
#define sz(x) (int)x.size()

using ll = long long;
using db = double;
using uint = unsigned;
using ull = unsigned long long;
using umapII = unordered_map<int, int>;
// PQ going up <int, VI, greater<int> >
using VI = vector<int>;
using VC = vector<char>;
using VS = vector<string>;
using VB = vector<bool>;
using VVB = vector<VB>;
using VVVB = vector<VVB>;
using VVVVB = vector<VVVB>;
using VVVVVB = vector<VVVVB>;
using VLL = vector<ll>;
using VVLL = vector<VLL>;
using VVVLL = vector<VVLL>;
using VVVVLL = vector<VVVLL>;
using VD = vector<db>;
using SI = set<int>;
using SS = set<string>;
using PII = pair<int, int>;
using PDD = pair<db, db>;
using PLL = pair<ll, ll>;
using VPI = vector<PII>;
using VVPI = vector<VPI>;
using VVI = vector<VI>;
using VVVI = vector<VVI>;
using VVVVI = vector<VVVI>;
using VVVVVI = vector<VVVVI>;
// mt19937 rng(chrono::high_resolution_clock::now().time_since_epoch().count() + reinterpret_cast<unsigned long>(new int) + *(new unsigned long));
void eraseDups(VI& a) {
    a.erase(unique(a.begin(), a.end()), a.end());
}
int strToInt(string&a) {
    stringstream x(a);
    int b;
    x >> b;
    return b;
}
int bitCnt(int a) {
    bitset <64> b(a);
    return b.count();
}
int bitCnt(string a) {
    bitset <64> b(a);
    return b.count();
}
VI readVI(int n) {
    VI a(n);
    REP(i, n) cin >> a[i];
    return a;
}
VVI readVVI(int n, int m) {
    VVI a(n, VI(m));
    REP(i, n) a[i] = readVI(m);
    return a;
}
VLL readVLL(ll n) {
    VLL a(n);
    REP(i, n) cin >> a[i];
    return a;
}
VVLL readVVLL(ll n, ll m) {
    VVLL a(n, VLL(m));
    REP(i, n) a[i] = readVLL(m);
    return a;
}


int gcd(int a, int b) {
   if (b == 0) return a;
   return gcd(b, a % b);
}

void print(VI& a) {
    for (auto el : a) {
        cout << el << ' ';
    }
    cout << '\n';
}
void print(VPI& a) {
    for (auto el : a) {
        cout << el.ff << ',' << el.ss << ' ';
    }
    cout << '\n';
}

void print(VI& a, int n) {
    int cnt = 0;
    for (auto el : a) {
        if (cnt++ == n) break;
        cout << el << ' ';
    }
    cout << '\n';
}
void print(VVI& a) {
    for (auto el : a) {
        print(el);
    }
}
const int MOD1 = 1e9 + 7;
const int MOD = 998244353;//7*19*2^23 +1;
const int INF = 1.07e9;
const ll INFF = INT64_MAX;
const db EPS = 1e-9;
const db PI = acos(-1.0); //M_PI;
const int dx[] = {-1, 0, 1, 0};
const int dy[] = {0, 1, 0, -1};
/*
|      ⣠⣶⡾⠏⠉⠙⠳⢦⡀⠀  ⠀⢠⠞⠉⠙⠲⡀
|    ⣴⠿⠏⠀⠀⠀⠀⠀⠀⢳⡀⠀  ⡏⠀⠀ ⠀⠀ ⢷
|⠀⠀⢠⣟⣋⡀⢀⣀⣀⡀⠀⣀⡀⣧⠀  ⢸⠀⠀⠀⠀   ⡇ ⠀
| ⠀⢸⣯⡭⠁⠸⣛⣟⠆⡴⣻⡲⣿   ⣸⠀⠀OK.  ⡇
|⠀⠀⣟⣿⡭⠀⠀⠀⠀⠀⢱⠀⠀⣿   ⢹⠀⠀⠀⠀⠀ ⡇
|⠀⠀⠙⢿⣯⠄⠀⠀⠀⢀⡀⠀⠀⡿⠀  ⡇⠀⠀ ⠀ ⡼
|⠀⠀⠀⠀⠹⣶⠆⠀⠀⠀⠀⠀⡴⠃ ⠀ ⠘⠤⣄⣠⠞⠀ ⠀
|⠀⠀⠀⠀⢸⣷⡦⢤⡤⢤⣞⣁⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀ ⠀
|⠀⢀⣤⣴⣿⣏⠁⠀⠀⠸⣏⢯⣷⣖⣦⡀⠀⠀⠀⠀⠀⠀
|⢀⣾⣽⣿⣿⣿⣿⠛⢲⣶⣾⢉⡷⣿⣿⠵⣿⠀⠀⠀⠀⠀
|⣼⣿⠍⠉⣿⡭⠉⠙⢺⣇⣼⡏⠀ ⠀⣄⢸⣿
|⣿⣿⣧⣀⣿.........⣀⣰⣏⣘⣆⣀
      
|                                                    _         _   _
|                                                   (_)       | | | |
 _ __  _ __ ___   __ _ _ __ __ _ _ __ ___  _ __ ___  _ ___ ___| |_| |_
| '_ \| '__/ _ \ / _` | '__/ _` | '_ ` _ \| '_ ` _ \| / __/ __| __| __|
| |_) | | | (_) | (_| | | | (_| | | | | | | | | | | | \__ \__ \ |_| |_
| .__/|_|  \___/ \__, |_|  \__,_|_| |_| |_|_| |_| |_|_|___/___/\__|\__|
| |               __/ |
|_|              |___/
 _   _      _ _    __        __         _     _ 
| | | | ___| | | __\ \      / /__  _ __| | __| |
| |_| |/ _ \ | |/ _ \ \ /\ / / _ \| '__| |/ _` |
|  _  |  __/ | | (_) \ V  V / (_) | |  | | (_| |
|_| |_|\___|_|_|\___/ \_/\_/ \___/|_|  |_|\__,_|                                  
 ____     __    _______    _______   __________
|     \  |  |  |  _____|  /  _____) |____  ____|
|  |\  \ |  |  | |__     (  (_____      |  |
|  | \  \|  |  |  __|     \_____  \     |  | 
|  |  \     |  | |_____    _____)  )    |  | 
|__|   \____|  |_______|  (_______/     |__| 
 
 
 


*/






const int N = 5000;

ll fact[N+5], invFact[N+5];
ll power(ll a, int b) {
    ll ans = 1; 
    while (b > 0) {
        if (b & 1) ans = (ans * a) % MOD;
        b >>= 1; 
        a = (a * a) % MOD;
    }
    return ans;
}
ll inv(ll a, ll p) {
    return power(a, p-2);
}
ll nCr(ll a, ll b) {
    if (a < b || b < 0) return 0;
    if (b == 0 || a == b) return 1;
    return fact[a] * invFact[b] % MOD * invFact[a - b] % MOD;
}
void init() {
    fact[0] = fact[1] = 1;
    for (int i = 2; i <= N; i++) fact[i] = fact[i-1] * i % MOD;
    invFact[N] = inv(fact[N], MOD);
    for (int i = N-1; i >= 0; i--) invFact[i] = invFact[i+1] * ll(i+1) % MOD;
}




ll n, k;
string s;
void go () {
    cin >> n >> k >> s;
    ll ans = 0;
    VI pos;
    for (int i = 0; i < n; i++) 
        if (s[i] == '1') pos.pb(i);

    if (k > pos.size() || k == 0) {
        cout << "1\n";
        return;
    }
    ll curLen = (pos.size() == k ? n : pos[k]), zero = 0;
    ans = (ans + nCr(curLen, k))%MOD;
    for (int i = pos[k], j = -1; i < n; i++) {
        if (s[i] == '1') {
            curLen = i - pos[++j];
            zero = curLen - k;
            if (zero > 0)
                ans = (ans + nCr(curLen-1, zero-1))%MOD;
        } else {
            curLen = i - pos[j];
            zero = curLen - k;
            ans = (ans + nCr(curLen-1, k-1))%MOD;
        }
    }
    cout << ans << '\n';
}



signed main () {

#ifndef ONLINE_JUDGE
    freopen("in.txt", "r", stdin);
    freopen("out.txt", "w", stdout);
#endif
    _upgrade
    int T = 1;
    // cin >> T;
    init();
    while(T--) go();
    return (0-0); //<3
}

/* stuff you should look for
    * int overflow, array bounds
    * special cases (n=1?)
    
*/