CALLING FUNCTION

// I am trying to call the function and passing it in a variable in main but it is giving me an error as
can’t resolve from void to int. can you suggest some alterantive
import java.util.*;

public class sanketAndStrings {

public static void main(String[] args) {
	Scanner scn = new Scanner(System.in);
	int n = scn.nextInt();


	Scanner sc = new Scanner(System.in);
	String str = sc.nextLine();

	if (n > str.length()) {
		System.out.println(str.length());
	}

//error here********
int ansa = ans(str,n,‘a’);
int ansb = ans(str,n,‘b’);
}

public static void ans(String str, int n, char ch) {
	int left = 0;
	int right = 0;
	int count = 0;
	int ans = 0;
	for (right = 0; right < str.length(); right++) {
		if (str.charAt(right) != ch) {
			count++;
		}
		if (count == n) {
			break;
		}
	}
	while (left < right) {
         while(str.charAt(right+1) == ch && (right< str.length()-1) ) {
        
        		 right++;
        	 
         }
         int currentlen = right-left+1;
         ans = Math.max(ans,currentlen);
         left++;
	}
	if(str.charAt(left-1) != ch && right < str.length()-1) {
		right++;
	}

}

}

see this: