Problem:
Score : 100 points

Problem Statement

Takahashi wants to print a document with N pages double-sided, where two pages of data can be printed on one sheet of paper.

At least how many sheets of paper does he need?

Constraints

N is an integer.

1 \leq N \leq 100

Input

Input is given from Standard Input in the following format:

N

Output

Print the answer.

Sample Input 1

5

Sample Output 1

3

By printing the 1-st, 2-nd pages on the 1-st sheet, 3-rd and 4-th pages on the 2-nd sheet, and 5-th page on the 3-rd sheet, we can print all the data on 3 sheets of paper.

Sample Input 2

2

Sample Output 2

1

Sample Input 3

100

Sample Output 3

50

Solution in Go (1.6) (judge verdict: Accepted)

package main

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

var huge = int(math.Pow(10, 18))

const maxS = 50*50 + 5

func main() {
	var n int
	InputInt(" ", &n)
	Write(n/2 + n%2)
	Flush()
}

/*----------文字列関連----------*/

// ReverseByte byte列の反転
func ReverseByte(list []byte) []byte {
	l := len(list)
	res := make([]byte, l)
	for i := 0; i < l; i++ {
		res[i] = list[l-i-1]
	}
	return res
}

/*----------Intでの基本計算関数----------*/

// MinInt 最大値導出関数
func MinInt(nums ...int) int {
	res := nums[0]
	for i := 0; i < len(nums); i++ {
		switch {
		case nums[i] < res:
			res = nums[i]
		}
	}
	return res
}

// MaxInt 最大値導出関数
func MaxInt(nums ...int) int {
	res := nums[0]
	for i := 0; i < len(nums); i++ {
		switch {
		case nums[i] > res:
			res = nums[i]
		}
	}
	return res
}

// PowInt Int型での冪乗計算
func PowInt(n int, x int) int {
	res := 1
	for i := 0; i < x; i++ {
		res *= n
	}
	return res
}

// SumInt Int型での合計計算
func SumInt(A ...int) int {
	sum := 0
	for _, a := range A {
		sum += a
	}
	return sum
}

// AbsInt Int型での絶対値計算
func AbsInt(x int) int {
	if x < 0 {
		x = -x
	}
	return x
}

/*----------Int型スライスの基本計算関数----------*/

// MinIntVec 最大値導出関数 インデックスも返す
func MinIntVec(nums []int) (int, []int) {
	res := nums[0]
	var index []int
	for i := 0; i < len(nums); i++ {
		switch {
		case nums[i] < res:
			res = nums[i]
			index = []int{i}
		case nums[i] == res:
			index = append(index, i)
		}
	}
	return res, index
}

// MaxIntVec 最大値導出関数 インデックスも返す
func MaxIntVec(nums []int) (int, []int) {
	res := nums[0]
	var index []int
	for i := 0; i < len(nums); i++ {
		switch {
		case nums[i] > res:
			res = nums[i]
			index = []int{i}
		case nums[i] == res:
			index = append(index, i)
		}
	}
	return res, index
}

// SumIntVec Int型での合計計算
func SumIntVec(A []int) int {
	sum := 0
	for _, a := range A {
		sum += a
	}
	return sum
}

/*----------標準入力・出力用の関数----------*/
var reader = bufio.NewReader(os.Stdin)
var writer = bufio.NewWriter(os.Stdout)

// InputLine 次の標準入力をstring型として取得
func InputLine() string {
	buffer := make([]byte, 0)
	for true {
		line, isPrefix, _ := reader.ReadLine()
		buffer = append(buffer, line...)
		if !isPrefix {
			break
		}
	}
	return string(buffer)
}

// InputString いくつかの文字列をstring型で取得
func InputString(delim string, A ...*string) {
	L := strings.Split(InputLine(), delim)
	for i, a := range A {
		*a = L[i]
	}
}

// InputStringVec delim区切りの文字列をstring型のスライスとして取得
func InputStringVec(delim string,A *[]string) {
	L := strings.Split(InputLine(), delim)
  *A = make([]string,len(L))
  for i := range L {
		(*A)[i] = L[i]
	}
}

// InputInt いくつかの数値をint型で取得
func InputInt(delim string, A ...*int) {
	L := strings.Split(InputLine(), delim)
	for i, a := range A {
		*a, _ = strconv.Atoi(L[i])
	}
}

// InputIntVec delim区切りの数値をint型のスライスとして取得
func InputIntVec(delim string, A *[]int) {
	L := strings.Split(InputLine(), delim)
	*A = make([]int, len(L))
	for i := range L {
		(*A)[i], _ = strconv.Atoi(L[i])
	}
}

// Write バッファに対応した出力関数
func Write(s interface{}) {
	fmt.Fprintln(writer, s)
}

// WriteIntVec バッファに対応したInt型スライスの出力関数
func WriteIntVec(A []int) {
	S := make([]string, len(A))
	for i, a := range A {
		S[i] = strconv.Itoa(a)
	}
	Write(strings.Join(S, " "))
}

// Flush バッファした出力をフラッシュ
func Flush() {
	_ = writer.Flush()
}