import java.util.*;


public class Solution {
    /**
     * 反转字符串
     * @param str string字符串 
     * @return string字符串
     */
    public String solve (String str) {
        //开玩笑的写法
        //return new StringBuilder(str).reverse()+"";
        char[] chars = str.toCharArray();
        for(int i=0; i<chars.length/2; i++){
            char temp = chars[i];
            chars[i]  = chars[chars.length-i-1];
            chars[chars.length-i-1] = temp;
        }
        return new String(chars);
    }
}