import java.util.*;
 
class Ideone {
    public static void main(String[] args) {
        String s = "abcfghij"; // Example string
        int k = 2;
 
        int n = s.length();
        int[] dp = new int[n];
        dp[0] = 1;
 
        int maxLen = 1, endIndex = 0;
 
        for (int i = 1; i < n; i++) {
            if (Math.abs(s.charAt(i) - s.charAt(i - 1)) <= k) {
                dp[i] = dp[i - 1] + 1;
            } else {
                dp[i] = 1;
            }
 
            if (dp[i] > maxLen) {
                maxLen = dp[i];
                endIndex = i;
            }
        }
 
        int startIndex = endIndex - maxLen + 1;
        System.out.println("Max length: " + maxLen);
        System.out.println("Substring: " + s.substring(startIndex, endIndex + 1));
    }
}
 

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