Largest Palindromic String

import java.io.*;
import java.util.*;

public class Solution {

    public static void main(String[] args) {
        Scanner sc=new Scanner(System.in);
        int t=sc.nextInt();
        while(t>0){
            int n=sc.nextInt();
            String str=sc.next();
            int ans=1;
            int x=n/2,p1,p2;
            char[] a=str.toCharArray();
            for(int i=0;i<n-1;i++){
                int l=1;
                if(a[i]==a[i+1]){
                    p1=i-1;
                    p2=i+2;
                    l++;
                    while(p1>=0 && p2<n){
                        if(a[p1]!=a[p2])
                            break;
                        l+=2;
                        p1--;
                        p2++;
                    }
                    ans=Math.max(ans,l);
                }
                l=1;
                if(i-1>=0 && i<n && a[i-1]==a[i+1]){
                    p1=i-1;
                    p2=i+1;
                    while(p1>=0 && p2<n){
                        if(a[p1]!=a[p2])
                            break;
                        l+=2;
                        p1--;
                        p2++;
                    }
                    ans=Math.max(ans,l);
                }
            }
            System.out.println(ans);
            t--;
        }
    }
}