luk2.go

package main

import (
	"bufio"
	"fmt"
	"io"
	"log"
	"os"
	"unicode"
)

func main() {
	reader := bufio.NewReader(os.Stdin)
	for {
		r, size, err := reader.ReadRune()
		if size == 0 {
			if err != io.EOF {
				log.Println("Error: ", err)
			}
			break
		}
		if unicode.IsUpper(r) {
			fmt.Print(string(r))
		}
	}
	fmt.Println()
}