#include<iostream.h>
#include<fstream.h>

ifstream f("suma.in");
ofstream g("suma.out");
double long n,p,y,i,s;
int main()
{
	f>>n;
	f>>p;
	s=(n*(n+1)*(2*n+1))/6-(n*(n+1))/2;
	cout<<s;
	if(s<p)
		g<<s;
	else
		g<<s-(unsigned long)(s/p)*p;
	
}