AtCoder Beginner Contest 394 (1)

A問題

package main

import (
	"fmt"
)

func main() {
	var s string

	fmt.Scan(&s)

	ss := []rune(s)

	var ans = ""

	for i := 0; i < len(ss); i++ {

		if ss[i] == '2' {
			ans = ans + string(ss[i])
		}
	}

	fmt.Println(ans)

}