using System;
public class Program
{
public static void Main()
int num=0, total=0, x=0;
do
Console.Write("กรุณาใส่ตัวเลข 1-100 : ");
num = int.Parse(Console.ReadLine());
}while(num <0 || num > 100);
while(x <= num){
total += x;
x++;
}
Console.WriteLine("\nSum of 0-{0} : {1}",num,total);