#include #include #include #include #include #include #include using namespace std; using ll = long long; using pii = pair; using vi = vector; using vvi = vector; // #define rep(i,n) for(int i=0;i<(n);++i) #define all(f,c,...) (([&](decltype((c)) cccc) { return (f)(begin(cccc), end(cccc), ## __VA_ARGS__); })(c)) #define _overload3(_1,_2,_3,name,...) name #define _rep(i,n) for(int i=0;i<(n);++i) #define repi(i,a,b) for(int i=(a);i<(b);++i) #define rep(...) _overload3(__VA_ARGS__,repi,_rep,)(__VA_ARGS__) #define _fromto2(i,n) for(int i=0;i<=(n);++i) #define _fromto3(i,a,b) for(int i=(a);i<=(b);++i) #define fromto(...) _overload3(__VA_ARGS__,_fromto3,_fromto2,)(__VA_ARGS__) #define rrep(i,n) for(int i=(n);i>=0;--i) const int MOD = 1e9+7; const int INF = 1e9; const int dx[4]={1,0,-1,0}, dy[4]={0,1,0,-1}; templatebool chmax(T &a,const T &b){if(abool chmin(T &a,const T &b){if(bostream& operator<<(ostream& os,const vector& vec){os<<"{";for(int i=0;iostream& operator<<(ostream& os,const pair& rhs){os<<"("< void debug(const First& first) {cerr< void debug(const First& first, const Rest&... rest) {cerr< struct Fp { long long val; constexpr Fp(long long v = 0) noexcept : val(v % MOD) { if (val < 0) val += MOD; } constexpr int getmod() { return MOD; } constexpr Fp operator - () const noexcept { return val ? MOD - val : 0; } constexpr Fp operator + (const Fp& r) const noexcept { return Fp(*this) += r; } constexpr Fp operator - (const Fp& r) const noexcept { return Fp(*this) -= r; } constexpr Fp operator * (const Fp& r) const noexcept { return Fp(*this) *= r; } constexpr Fp operator / (const Fp& r) const noexcept { return Fp(*this) /= r; } constexpr Fp& operator += (const Fp& r) noexcept { val += r.val; if (val >= MOD) val -= MOD; return *this; } constexpr Fp& operator -= (const Fp& r) noexcept { val -= r.val; if (val < 0) val += MOD; return *this; } constexpr Fp& operator *= (const Fp& r) noexcept { val = val * r.val % MOD; return *this; } constexpr Fp& operator /= (const Fp& r) noexcept { long long a = r.val, b = MOD, u = 1, v = 0; while (b) { long long t = a / b; a -= t * b; swap(a, b); u -= t * v; swap(u, v); } val = val * u % MOD; if (val < 0) val += MOD; return *this; } constexpr bool operator == (const Fp& r) const noexcept { return this->val == r.val; } constexpr bool operator != (const Fp& r) const noexcept { return this->val != r.val; } friend constexpr ostream& operator << (ostream &os, const Fp& x) noexcept { return os << x.val; } friend constexpr Fp modpow(const Fp &a, long long n) noexcept { if (n == 0) return 1; auto t = modpow(a, n / 2); t = t * t; if (n & 1) t = t * a; return t; } }; using mint = Fp; int main() { int N, _p; cin >> N >> _p; mint p(_p); mint A[N]; A[0] = 0; A[1] = 1; rep(i, N-2) { A[i+2] = p * A[i+1] + A[i]; } mint ans = 0; mint acc; rep(i, N) { acc += A[i]; ans += A[i] * acc; } cout << ans << endl; return 0; }