countMaxOfZeroesOrOnes

import java.util.*;
public class machine {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner sc = new Scanner (System.in);
        int n = sc.nextInt ();
        String str = sc.next ();
        int max = 0, count = 0;
        char ch = str.charAt (n - 1);
        int i = n - 1;
    
        while (str.charAt (i) == ch)
            i--;
        str = str.substring (0, i + 1);

        ch = str.charAt (0);
        i = 0;
        while (str.charAt (i) == ch)
            i++;
        str = str.substring (i);
    
        int countZero = 0, countOne = 0;
        
        for (i = 0; i < str.length (); i++)
        {
	        if (str.charAt (i) == '0')
	            countZero++;
	        else
	            countZero = 0;
	        if (str.charAt (i) == '1')
	            countOne++;
	        else
	            countOne = 0;
	        max = Math.max (max, Math.max (countZero, countOne));
        }
        System.out.println (max);
	}

}