description: You are given a binary string (i. e. a string consisting of characters 0 and/or 1) s of length n. You can perform the following operation with the string s at most once: choose a substring (a contiguous subsequence) of s having exactly k characters 1 in it, and shuffle it (reorder the characters in the substring as you wish).
  
  Calculate the number of different strings which can be obtained from s by performing this operation at most once.
  
  Input
  
  The first line contains two integers n and k (2 ≤ n ≤ 5000; 0 ≤ k ≤ n).
  
  The second line contains the string s of length n, consisting of characters 0 and/or 1.
  
  Output
  
  Print one integer — the number of different strings which can be obtained from s by performing the described operation at most once. Since the answer can be large, output it modulo 998244353.
  
  Examples
  
  Input
  
  
  7 2
  1100110
  
  
  Output
  
  
  16
  
  
  Input
  
  
  5 0
  10010
  
  
  Output
  
  
  1
  
  
  Input
  
  
  8 1
  10001000
  
  
  Output
  
  
  10
  
  
  Input
  
  
  10 8
  0010011000
  
  
  Output
  
  
  1
  
  Note
  
  Some strings you can obtain in the first example:
  
    * to obtain 0110110, you can take the substring from the 1-st character to the 4-th character, which is 1100, and reorder its characters to get 0110; 
    * to obtain 1111000, you can take the substring from the 3-rd character to the 7-th character, which is 00110, and reorder its characters to get 11000; 
    * to obtain 1100101, you can take the substring from the 5-th character to the 7-th character, which is 110, and reorder its characters to get 101. 
  
  
  
  In the second example, k = 0 so you can only choose the substrings consisting only of 0 characters. Reordering them doesn't change the string at all, so the only string you can obtain is 10010.
solution: import java.util.*;
  import java.io.*;
  
  ////***************************************************************************
   /* public class E_Gardener_and_Tree implements Runnable{
  
         public static void main(String[] args) throws Exception {
          new Thread(null, new E_Gardener_and_Tree(), "E_Gardener_and_Tree", 1<<28).start();
         }
      public void run(){
           WRITE YOUR CODE HERE!!!!
           JUST WRITE EVERYTHING HERE WHICH YOU WRITE IN MAIN!!!
         }
  
    }
  */
  /////**************************************************************************
  
  
  public class D_Shuffle{
      public static void main(String[] args) {
          FastScanner s= new FastScanner();
          //PrintWriter out=new PrintWriter(System.out);
          //end of program
          //out.println(answer);
          //out.close();
          StringBuilder res = new StringBuilder();
          int n=s.nextInt();
          int k=s.nextInt();
          String str=s.nextToken();
          if(k==0){
              System.out.println("1");
              return;
          }
          long mod=998244353;
          long fact[]= new long[n+5];
          long infact[]= new long[n+5];
  
          fact[0]=1;
          fact[1]=1;
          for(int i=2;i<n+5;i++){
              fact[i]=(fact[i-1]*i)%mod;
          }
          for(int i=0;i<n+5;i++){
              infact[i]=modpower(fact[i],mod-2,mod);
          }
          long ans=0;
          int flag=0;
          for(int i=0;i<n;i++){
              long count=0;
            //  System.out.println("i "+i);
              int j=i;
                for(;j<n;j++){
                    char ch=str.charAt(j);
                    if(ch=='1'){
                        count++;
                    }
                    if(count>k){
                        break;
                    }
                }
             //   System.out.println("j "+j);
  
                if(count>=k){
                    flag=1;
                   // String str2=str.substring(i,j);
                    long len=j-i;
                    long ones=k;
                    long zeroes=len-ones;
                    long yoyo1=(fact[(int)len]*infact[(int)ones])%mod;
                    yoyo1=(yoyo1*infact[(int)zeroes])%mod;
                    long yoyo2=0;
                    if(count>k){
                        int l=i;
                        for(;l<n;l++){
                            char ch=str.charAt(l);
                            if(ch=='1'){
                                break;
                            }
                        }
                        l++;
                     //   System.out.println("l "+l);
                        i=l-1;
                        long len1=j-l;
                        long ones1=k-1;
                        long zeroes1=len1-ones1;
                        yoyo2=(fact[(int)len1]*infact[(int)ones1])%mod;
                        yoyo2=(yoyo2*infact[(int)zeroes1])%mod;
  
                    }
                    else{
                        i=n;
                    }
                    long hh=(yoyo1-yoyo2+mod)%mod;
                    ans=(ans+hh)%mod;
                    ans=(ans+mod)%mod;
                }
                else{
                    break;
                }
              //   System.out.println("kkk "+ans);
              //   System.out.println();
  
          }
          if(flag==0){
              ans++;
          }
          res.append(ans+" \n");
          System.out.println(res);
  
  
      }
      static class FastScanner {
  		BufferedReader br;
  		StringTokenizer st;
   
  		public FastScanner(String s) {
  			try {
  				br = new BufferedReader(new FileReader(s));
  			} catch (FileNotFoundException e) {
  				// TODO Auto-generated catch block
  				e.printStackTrace();
  			}
  		}
   
  		public FastScanner() {
  			br = new BufferedReader(new InputStreamReader(System.in));
  		}
   
  		String nextToken() {
  			while (st == null || !st.hasMoreElements()) {
  				try {
  					st = new StringTokenizer(br.readLine());
  				} catch (IOException e) {
  					// TODO Auto-generated catch block
  					e.printStackTrace();
  				}
  			}
  			return st.nextToken();
  		}
   
  		int nextInt() {
  			return Integer.parseInt(nextToken());
  		}
   
  		long nextLong() {
  			return Long.parseLong(nextToken());
  		}
   
  		double nextDouble() {
  			return Double.parseDouble(nextToken());
  		}
  	}
  
  
      static long modpower(long x, long y, long p)
       {
        long res = 1; // Initialize result
     
        x = x % p; // Update x if it is more than or
        // equal to p
     
        if (x == 0)
          return 0; // In case x is divisible by p;
     
        while (y > 0)
        {
     
          // If y is odd, multiply x with result
          if ((y & 1) != 0)
            res = (res * x) % p;
     
          // y must be even now
          y = y >> 1; // y = y/2
          x = (x * x) % p;
        }
        return res;
      }
  
    
     // SIMPLE POWER FUNCTION=>
  
  
        static long power(long x, long y)
          {
              long res = 1;     // Initialize result
          
              while (y > 0)
              {
              
                  // If y is odd, multiply x with result
                  if ((y & 1) != 0)
                      res = res * x;
          
                  // y must be even now
                  y = y >> 1; // y = y/2
                  x = x * x;  // Change x to x^2
              }
              return res;
          }
  
  
  
  
  
  }