import java.io.*;
class prbwhile2 
{
	public static void main(String Arg[ ]) throws IOException
	{
		int i = 1;
		int sum = 0;
		int num;
         
		BufferedReader in = new BufferedReader(new 
			InputStreamReader(System.in));

		System.out.print("Ingrese numero : ");
		num = Integer.parseInt(in.readLine( ));
        
		while (i <= num)
		{
			if (i % 3 == 0)
			{
				sum += i;
			}
			i++;
		}
       	
       	System.out.println("sumatoria : " + sum );
	}
}