/* package whatever; // don't place package name! */
 
import java.util.*;
import java.lang.*;
import java.io.*;
 
/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
	public static void main (String[] args) throws java.lang.Exception
	{
		System.out.println(subStrMaxC("abcabcabc", 'c', 1));
	}
	static int subStrMaxC(String s, char c, int k){
		int result = 0;
		int count = 0;
		for(int i = 0; i < s.length(); i++){
    		if(s.charAt(i) == c){
    			result += Integer.min(k + 1, count);
    			count++;
    		}
		}	
    	return result;
	}
 
 
}

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