Problem:
Score : 100 points

Problem Statement

An uppercase or lowercase English letter \alpha will be given as input.
If \alpha is uppercase, print A; if it is lowercase, print a.

Constraints

\alpha is an uppercase (A - Z) or lowercase (a - z) English letter.

Input

Input is given from Standard Input in the following format:

α

Output

If \alpha is uppercase, print A; if it is lowercase, print a.

Sample Input 1

B

Sample Output 1

A

B is uppercase, so we should print A.

Sample Input 2

a

Sample Output 2

a

a is lowercase, so we should print a.

Solution in Go (1.14.1) (judge verdict: Wrong Answer)

package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
	"strings"
)

type Io struct {
	reader    *bufio.Reader
	writer    *bufio.Writer
	tokens    []string
	nextToken int
}

func NewIo() *Io {
	return &Io{
		reader: bufio.NewReader(os.Stdin),
		writer: bufio.NewWriter(os.Stdout),
	}
}

func (io *Io) Flush() {
	if err := io.writer.Flush(); err != nil {
		panic(err)
	}
}

func (io *Io) NextLine() string {
	var buffer []byte
	for {
		line, isPrefix, err := io.reader.ReadLine()
		if err != nil {
			panic(err)
		}
		buffer = append(buffer, line...)
		if !isPrefix {
			break
		}
	}
	return string(buffer)
}

func (io *Io) Next() string {
	for io.nextToken >= len(io.tokens) {
		line := io.NextLine()
		io.tokens = strings.Fields(line)
		io.nextToken = 0
	}
	r := io.tokens[io.nextToken]
	io.nextToken++
	return r
}

func (io *Io) NextInt() int {
	i, err := strconv.Atoi(io.Next())
	if err != nil {
		panic(err)
	}
	return i
}

func (io *Io) NextFloat() float64 {
	i, err := strconv.ParseFloat(io.Next(), 64)
	if err != nil {
		panic(err)
	}
	return i
}

func (io *Io) PrintLn(a ...interface{}) {
	fmt.Fprintln(io.writer, a...)
}

func (io *Io) Printf(format string, a ...interface{}) {
	fmt.Fprintf(io.writer, format, a...)
}

func (io *Io) PrintIntLn(a []int) {
	b := []interface{}{}
	for _, x := range a {
		b = append(b, x)
	}
	io.PrintLn(b...)
}

func (io *Io) PrintStringLn(a []string) {
	b := []interface{}{}
	for _, x := range a {
		b = append(b, x)
	}
	io.PrintLn(b...)
}

func Log(name string, value interface{}) {
	fmt.Fprintf(os.Stderr, "%s=%+v\n", name, value)
}

func intMin(a, b int) int {
	if a < b {
		return a
	}
	return b
}

func intMax(a, b int) int {
	if a > b {
		return a
	}
	return b
}

func main() {
	io := NewIo()
	defer io.Flush()
	A := io.Next()
	io.PrintLn(strings.ToLower(A))
}