hdu1001

//c
#include "stdio.h"
int main() {
int a = 0, sum = 0;
while (scanf("%d", & a) != EOF) {
if ((a << 31) >> 31 == 0) {
sum = a / 2;
sum *= a + 1;
printf("%d\n\n", sum);
} else {
sum = (a + 1) / 2;
sum *= a;
printf("%d\n\n", sum);
}
}
return 0;
}

//c++
#include "iostream"
using namespace std;
int main() {
int a = 0, sum = 0;
while (cin >> a) {
if ((a << 31) >> 31 == 0) {
sum = a / 2;
sum *= a + 1;
cout << sum << endl;
cout << endl;
} else {
sum = (a + 1) / 2;
sum *= a;
cout << sum << endl;
cout << endl;
}
}
return 0;
}

//c#
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace csharp {
class Program {
static void Main(string[] args) {
string s;
int a, sum;
while ((s = Console.ReadLine()) != null) {
a = Convert.ToInt32(s);
if ((a << 31) >> 31 == 0) {
sum = a / 2;
sum *= a + 1;
Console.WriteLine("{0}\n\n", sum);
} else {
sum = (a + 1) / 2;
sum *= a;
Console.WriteLine("{0}\n\n", sum);
}
}
}
}
}

//java
import java.util.Scanner;
public class Main {
public static void main(String args[]) {
Scanner s = new Scanner(System. in );
while (s.hasNextInt()) {
int n = s.nextInt();
if ((n << 31) >> 31 == 0) {
int sum = n / 2;
sum = sum * (n + 1);
System.out.println(sum);
System.out.println();
} else {
int sum = (n + 1) / 2;
sum = sum * n;
System.out.println(sum);
System.out.println();
}
}
}
}