#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); i++)
using namespace std;
using ll = long long;
using P = pair<int,int>;

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int n, k;
    cin >> n >> k;
    ll ans = 0;
    for(int i = 2; i <= 2*n; i++){
        if(i + k > 2*n) continue;
        if(i + k < 2) continue;
        ll tmp;
        if(i <= n+1) tmp = i-1;
        else tmp = 2*n-i+1;
        if(i + k <= n+1) tmp *= k + i - 1;
        else tmp *= 2*n - k - i + 1;
        ans += tmp;
    }
    cout << ans << endl;
}
#include <iostream>
#include <algorithm>
#include<cmath>
#include<cstring>
#include<cstdio>
#include<cstdlib>
#include<vector>
#include<iomanip>
#include<ctime>
#include<set>
#include<map>
#include<queue>
#include<stack>
#include<bitset>
#define sqr(x) ((x)*(x))
#define fz1(i,n) for ((i)=1;(i)<=(n);(i)++)
#define fd1(i,n) for ((i)=(n);(i)>=1;(i)--)
#define fz0g(i,n) for ((i)=0;(i)<=(n);(i)++)
#define fd0g(i,n) for ((i)=(n);(i)>=0;(i)--)
#define fz0k(i,n) for ((i)=0;(i)<(n);(i)++)
#define fd0k(i,n) for ((i)=(long long)((n)-1);(i)>=0;(i)--)
#define fz(i,x,y) for ((i)=(x);(i)<=(y);(i)++)
#define fd(i,y,x) for ((i)=(y);(i)>=(x);(i)--)
#define fzin fz1(i,n)
#define fzim fz1(i,m)
#define fzjn fz1(j,n)
#define fzjm fz1(j,m)
#define ff(c,itr) for (__typeof((c).begin()) itr=(c).begin();itr!=(c).end();++itr)
#define pb push_back
#define mk make_pair
#define rdst(st,len){static char ss[len];scanf(" %s",ss);(st)=ss;}
#define inc(x,y) {x+=(y);if(x>=mod)x-=mod;}
#define dec(x,y) {x-=(y);if(x<0)x+=mod;}
#define spln(i,n) (i==n?'\n':' ')
#define fac_init(n){fac[0]=fac[1]=inv[1]=fi[0]=fi[1]=1;fz(i,2,n){fac[i]=1ll*fac[i-1]*i%mod;inv[i]=1ll*(mod-mod/i)*inv[mod%i]%mod;fi[i]=1ll*fi[i-1]*inv[i]%mod;}}
using namespace std;
inline void read(int &x)
{
	char c;int f=1;
	while(!isdigit(c=getchar()))if(c=='-')f=-1;
	x=(c&15);while(isdigit(c=getchar()))x=(x<<1)+(x<<3)+(c&15);
	x*=f;
}
long long n,m,i,ans;
long long f(long long x)
{
	if(x<2||x>n+n) return 0;
	return min(x-2+1,n+n-x+1);
}
int main()
{
	cin>>n>>m;
	fz(i,2,n+n){
		ans+=f(i+m)*f(i);
	}
	cout<<ans<<endl;
	return 0;
}












