can anyone tell me what is wrong in this code?
import java.util.*;
public class Main {
public static void main(String args[]) {
Scanner scn = new Scanner(System.in);
// Scanner s=new Scanner(System.in);
int k = scn.nextInt();
String str = scn.nextLine();
change_string(str, k);
}
public static void change_string(String s, int k) {
int i, m = 0;
for (i = 0; i < 2; i++) {
int t = k;
int l = 0, r = 0;
char ch = (char) ('a' + i);
while (r < s.length()) {
if (s.charAt(r) != ch && t == 0) {
m = Math.max(m, r - l);
while (t == 0) {
if(s.charAt(l)!=ch) {
t++;
}
l++;
}
} else if (s.charAt(r) != ch) {
r++;
t--;
} else {
r++;
}
m = Math.max(m, r - l);
}
}
System.out.println(m);
}
}