Problem:
Score : 100 points

Problem Statement

There are N children in AtCoder Kindergarten. Mr. Evi will arrange the children in a line, then give 1 candy to the first child in the line, 2 candies to the second child, ..., N candies to the N-th child. How many candies will be necessary in total?

Constraints

1≦N≦100

Input

The input is given from Standard Input in the following format:

N

Output

Print the necessary number of candies in total.

Sample Input 1

3

Sample Output 1

6

The answer is 1+2+3=6.

Sample Input 2

10

Sample Output 2

55

The sum of the integers from 1 to 10 is 55.

Sample Input 3

1

Sample Output 3

1

Only one child. The answer is 1 in this case.

Solution in Java8 (OpenJDK 1.8.0) (judge verdict: Wrong Answer)

import java.io.*;
import java.util.*;
public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
 

//     String[] nyu=sc.nextLine().split(" ");

     String nyu=sc.nextLine();
//int A=Integer.parseInt(nyu[0]);
//int B=Integer.parseInt(nyu[1]);
//int C=Integer.parseInt(nyu[2]);
int D=Integer.parseInt(nyu);



//StringBuffer sb = new StringBuffer(nyu);
//		String dst = sb.reverse().toString();

//     String nyu2=sc.nextLine();
//int E=Integer.parseInt(nyu2);



//double A=Double.parseDouble(nyu[0]);
//double B=Double.parseDouble(nyu[1]);
/*
switch(nyu){
case "H H":
System.out.println("H") ;
break;

case "D D":
System.out.println("H") ;
break;

case "H D":
System.out.println("D") ;
break;

case "D H":
System.out.println("D") ;
break;


default:
System.out.println("NO") ;

break;
}
*/

//int res=Math.min((A*B),C);

//for(String tem:bo){
//if(tem.equals(nyu))res="vowel";
//}
//int res=0;
//for(int i=0;i<300;i++){
//if(num[i]==1)res=i;
//}

//char[] c = nyu.toCharArray();


//System.out.println(nyu+"-"+line_r_2+"-"+nyu2+"-"+line_r_1);

int res=0;
for(int i=1;i<D;i++){
res+=i;
}

//if(D<=E){
//double res=Math.ceil((AB)/2);

//System.out.println(D*F);
//}else if(B<A){
//System.out.println("Alice");

//}else{
System.out.println(res);
//}




	}
}