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) {
        char[] chs = str.toCharArray();
        StringBuilder sb = new StringBuilder();
        for (int i = chs.length-1; i >=0 ; i--) {
            sb.append(chs[i]);
        }
        return sb.toString();
    }
}