```go
package main

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

func main() {
	in := bufio.NewReader(os.Stdin)
	var t string
	fmt.Fscan(in, &t)

	n := len(t)
	s := make([]byte, n)

	left := (n - 1) / 2
	right := left + 1

	for i := 0; i < n; i++ {
		if i%2 == 0 {
			s[i] = t[left]
			left--
		} else {
			s[i] = t[right]
			right++
		}
	}

	fmt.Print(string(s))
}
```