Make S into an alternate binary string by changing any character with 0 or 1 as much as Okay instances

import java.util.*;

public class GFG {

    public static void essential(String[] args)

    {

        String str = "akmzaxazmk";

        int Okay = 6;

        AlterString(str, Okay);

    }

    static void AlterString(String str, int Okay)

    {

        boolean flag = true;

        HashMap<Character, Integer> map = new HashMap<>();

        for (int i = 0; i < str.size(); i++) {

            if (map.containsKey(str.charAt(i))) {

                int finish = map.get(str.charAt(i));

                if ((finish - i) % 2 == 0) {

                    proceed;

                }

                else {

                    flag = false;

                    break;

                }

            }

            else {

                map.put(str.charAt(i), i);

            }

        }

        if (flag && map.measurement() <= Okay) {

            System.out.println("YES");

            for (Map.Entry<Character, Integer> set :

                 map.entrySet()) {

                System.out.println(

                    " " + set.getKey() + " : "

                    + ((set.getValue() % 2 == 0) ? 0 : 1));

            }

        }

        else {

            System.out.println("NO");

        }

    }

}