#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
typedef long long ll;
typedef pair<ll,ll> P;
typedef modint1000000007 mint;
#define rep(i,a,b) for(ll i=a;i<b;i++)
#define rrep(i,a,b) for(ll i=a;i>=b;i--)
const ll inf=1e18;
ll n,p;
mint ans,a[2000005],s[2000005];
int main(void){
    cin.tie(0);
    ios::sync_with_stdio(0);
    cin>>n>>p;
    if(n==1){
        cout<<0<<endl;
        return 0;
    }
    a[0]=0;
    a[1]=1;
    s[1]=0;
    s[2]=1;
    ans=1;
    rep(i,2,n){
        a[i]=p*a[i-1]+a[i-2];
        s[i+1]=s[i]+a[i];
        ans+=(a[i]*s[i+1]);
    }
    cout<<ans.val()<<endl;

}