/*
*/

//#pragma comment(linker, "/STACK:16777216")
#include <fstream>
#include <iostream>
#include <string>
#include <complex>
#include <math.h>
#include <set>
#include <vector>
#include <map>
#include <queue>
#include <stdio.h>
#include <stack>
#include <algorithm>
#include <list>
#include <ctime>
#include <memory.h>
#include <ctime>

#define y0 sdkfaslhagaklsldk
#define y1 aasdfasdfasdf
#define yn askfhwqriuperikldjk
#define j1 assdgsdgasghsf
#define tm sdfjahlfasfh
#define lr asgasgash

#define eps 1e-9
//#define M_PI 3.141592653589793
#define bs 1000000007
#define bsize 256
#define right adsgasgadsg
#define free adsgasdg
#define count adsgasdgasdg

using namespace std;

long n;
long iterations;

vector<long> g[1<<20];
long sub[1<<20];
long k;

void dfs(long v)
{
 vector<long> sons;
 for (int i=0;i<g[v].size();i++)
 {
  long id=g[v][i];
  dfs(id);
  sons.push_back(id);
 }

 for (int i=0;i<sons.size();i++)
 {
  iterations+=k*sub[v];
  sub[v]+=sub[sons[i]];
  if (sub[v]>k)sub[v]=k;
 }
 sub[v]++;
}

int main(){
//freopen("k.in","r",stdin);
//freopen("k.out","w",stdout);
//freopen("C:/input.txt","r",stdin);
//freopen("C:/output.txt","w",stdout);
ios_base::sync_with_stdio(0);
//cin.tie(0);

cin>>n;
cin>>k;

for (int i=1;i<=k;i++)
{
 g[i].push_back(i+1);
}

for (int i=k+2;i<=n;i++)
{
    g[1].push_back(i);
}

dfs(1);

cout<<iterations<<endl;
/*
for (int i=1;i<=n;i++)
cout<<sub[i]<<" ";*/

cin.get();cin.get();
return 0;}