HD1001 java版答案

import java.util.Scanner;

public class acm2{

public static void main(String[] args) {

Scanner sc = new Scanner(System.in);

long n, i, sum = 0;

while (sc.hasNext()) {

n = sc.nextLong();

sum = 0;

for (i = 1; i <= n; i++) {

sum = sum + i;

}

System.out.println(sum);

System.out.print("\n\n");

}

}

}