import java.util.Scanner;

/**
 * @author wuze
 * @desc ...
 * @date 2021-03-21 18:43:27
 */
public class 百度笔试1_数字跳跃 {
    public static void main(String[] args){
        Scanner in = new Scanner(System.in);
        int len = Integer.parseInt(in.nextLine());
        int[] nums=new int[len+1];
        int count=0;
        int flag=0;
        String s=in.nextLine();

        for (int i=0;i<len;i++){
            nums[i]=Integer.parseInt(s.substring(i,i+1));
        }


        for(int index=0;index<len;index++){
            flag=0;
            for(int j=index+1;j<len;j++){
                if(nums[index]==nums[j] && flag==0){
                    flag=1;
                    index=j;
                    count++;
                    continue;
                }
            }
            if(flag!=1){
                index++;
                count++;
            }

        }
        System.out.println(count+1);
    }
}