public class N7 {
    public static long f1(int a)
    {
        long sum=0;
        int i;
        for(i=3 ; i <= a ; i=i+3)
            sum=sum+i;
        return sum;
    }

    public static void main(String[] args)
    {
        int x1=10, x2=20, x3=83;
        long y1,y2,y3;
        y1=f1(x1);
        y2=f1(x2);
        y3=f1(x3);
        System.out.println(y1);
        System.out.println(y2);
        System.out.println(y3);
    }
}