合并数组

import java.util.*;
public class Main {


    public static void main(String[] args){
        Scanner in = new Scanner(System.in);
        while(in.hasNext()){
            int k = Integer.parseInt(in.next());
            int n = Integer.parseInt(in.next());
            String[] arr = new String[n];
            for(int i=0; i<n; i++){
                arr[i] = in.next();
            }
            boolean[] isEmpty = new boolean[n];
            //System.out.println(Merge(arr, 0, isEmpty, 0, "", k));
            System.out.println(Merge(arr, k));
        }
    }

    //public static String Merge(String[] arr, int i, boolean[] isEmpty, int cur, String res, int k){
    //    boolean isEnd =true;
    //    for(boolean flag:isEmpty){
    //        if(!flag) isEnd = false;
    //    }
    //    if(isEnd) return res;
    //    if(i== arr.length) return Merge(arr, 0, isEmpty, cur+k, res, k);
    //    if(isEmpty[i]){
    //         return Merge(arr, i+1, isEmpty, cur, res, k);
    //    } else {
    //        if(cur+k<=arr[i].length()){
    //            return Merge(arr, i+1, isEmpty, cur, res+arr[i].substring(cur, cur+k), k);
    //        } else {
    //            isEmpty[i] = true;
    //            return Merge(arr, i+1, isEmpty, cur, res+arr[i].substring(cur), k);
    //        }
    //    }
    //}

    public static String Merge(String[] arr, int k){
        String res = "";
        List<String[]> list = new ArrayList<>();
        int total = 0;
        for(String s:arr){
            String[] sa = s.split(",");
            list.add(sa);
            total += sa.length;
        }
        int cur = 0;
        while(res.split(",").length < total){
            for(int i=0; i<arr.length; i++){
                String[] temp = list.get(i);
                for(int j=cur; j<temp.length&&j<cur+k; j++){
                    res += temp[j]+",";
                }
            }
            cur += k;

        }
        return res.substring(0, res.length()-1);
    }
}