#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
#define REP(i, n) for (int i = 0; i < (n); ++i)
#define REPR(i, n) for (int i = n - 1; i >= 0; --i)
#define FOR(i, m, n) for (int i = m; i < n; ++i)
#define FORR(i, m, n) for (int i = m; i >= n; --i)
#define ALL(v) (v).begin(),(v).end()
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }
const ll INF=1LL<<60;
const int inf=(1<<30)-1;
const int mod=1e9+7;
int dx[8]={1,0,-1,0,-1,-1,1,1};
int dy[8]={0,1,0,-1,-1,1,-1,1};
ll pow_mod(ll n,ll k,ll m){
  ll res=1;
  for(;k>0;k>>=1){
    if(k&1){
      res=(res*n)%m;
    }
    n=(n*n)%m;  
  }
  return res;
}

ll mod_inv(ll a, ll m){
	return pow_mod(a,m-2,m);
}
int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);
    ll n,p;cin >> n >> p;
    cout << (p-1)*pow_mod(p-2,n-1,mod)%mod << endl;
}
#include<bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i,s,t) for(int i = (int)(s); i < (int)(t); i++)
using p = pair<int,int>;

ll func(int n, int k){
    return max(0, min(k - 1, 2*n + 1 - k));
}

int main(){
    int n,k;
    cin >> n >> k;
    ll ans = 0;
    rep(i,2,2*n+1){
        ans += func(n, k + i) * func(n, i);
    }
    cout << ans << endl;
}