Example_for_4

using System;
using System.Collections.Generic;
using System.Linq;

class MainClass {
    static void Main() {
        Random rnd = new Random();
        int x = rnd.Next(1, 100);
        Console.WriteLine(x);
        int sum = 0;
        for(int i = 1; i <= x; i++){
            sum += i; 
        }
        Console.WriteLine("---------");
        Console.WriteLine(sum);
        
        
    }
}