#include #include #include #include #include #include #include #include #include #include #include static const int MOD = 1000000007; using ll = long long; using u32 = unsigned; using u64 = unsigned long long; using namespace std; template constexpr T INF = ::numeric_limits::max()/32*15+208; template struct modint{ u32 val; modint(): val(0){} template modint(T t){t %= (T)M; if(t < 0) t += (T)M; val = t;} modint pow(ll k) const { modint res(1), x(val); while(k){ if(k&1) res *= x; x *= x; k >>= 1; } return res; } template modint& operator=(T t){t %= (T)M; if(t < 0) t += (T)M; val = t; return *this;} modint inv() const {return pow(M-2);} modint& operator+=(modint a){val += a.val; if(val >= M) val -= M; return *this;} modint& operator-=(modint a){if(val < a.val) val += M-a.val; else val -= a.val; return *this;} modint& operator*=(modint a){val = (u64)val*a.val%M; return *this;} modint& operator/=(modint a){return (*this) *= a.inv();} modint operator+(modint a) const {return modint(val) +=a;} modint operator-(modint a) const {return modint(val) -=a;} modint operator*(modint a) const {return modint(val) *=a;} modint operator/(modint a) const {return modint(val) /=a;} modint operator-(){return modint(M-val);} bool operator==(const modint a) const {return val == a.val;} bool operator!=(const modint a) const {return val != a.val;} bool operator<(const modint a) const {return val < a.val;} }; using mint = modint; int main() { int n, p; cin >> n >> p; vector v(n); v[0] = 0; v[1] = 1; for (int i = 2; i < n; ++i) { v[i] = mint(p)*v[i-1]+v[i-2]; } auto x = accumulate(v.begin(),v.end(), mint(0)); mint y; for (int i = 0; i < n; ++i) { y += v[i]*v[i]; } cout << ((x*x-y)*mint(500000004)+y).val << "\n"; return 0; }