package main

import(
    "bufio"
    "fmt"
    "os"
)

func main(){
    scanner := bufio.NewScanner(os.Stdin)
    scanner.Scan()
    s := scanner.Text()
    arr := []rune(s)
    for left,right := 0,len(arr) - 1;left < right;left++{
        arr[left],arr[right] = arr[right],arr[left]
        right --
    }     
    fmt.Println(string(arr))
}

双指针，通用性拉满