// >>> TEMPLATES #include using namespace std; using ll = long long; using ld = long double; #define int ll #define double ld #define rep(i,n) for (int i = 0; i < (int)(n); i++) #define rep1(i,n) for (int i = 1; i <= (int)(n); i++) #define repR(i,n) for (int i = (int)(n)-1; i >= 0; i--) #define rep1R(i,n) for (int i = (int)(n); i >= 1; i--) #define loop(i,a,B) for (int i = a; i B; i++) #define loopR(i,a,B) for (int i = a; i B; i--) #define all(x) (x).begin(), (x).end() #define allR(x) (x).rbegin(), (x).rend() #define pb push_back #define eb emplace_back #define mp make_pair #define fst first #define snd second #define INF (numeric_limits::max()/2-1) #ifdef LOCAL #include "debug.hpp" #define dump(...) cerr << "[" << __LINE__ << ":" << __FUNCTION__ << "] ", dump_impl(#__VA_ARGS__, __VA_ARGS__) #define say(x) cerr << "[" << __LINE__ << ":" << __FUNCTION__ << "] " << x << endl #define debug if (1) #else #define dump(...) (void)(0) #define say(x) (void)(0) #define debug if (0) #endif template using pque_max = priority_queue; template using pque_min = priority_queue, greater >; template ::value>::type> ostream& operator<<(ostream& os, T const& v) { bool f = true; for (auto const& x : v) os << (f ? "" : " ") << x, f = false; return os; } template ::value>::type> istream& operator>>(istream& is, T &v) { for (auto& x : v) is >> x; return is; } template istream& operator>>(istream& is, pair& p) { return is >> p.first >> p.second; } struct IOSetup { IOSetup() { cin.tie(nullptr); ios::sync_with_stdio(false); cout << fixed << setprecision(15); } } iosetup; template struct FixPoint : private F { constexpr FixPoint(F&& f) : F(forward(f)) {} template constexpr auto operator()(T&&... x) const { return F::operator()(*this, forward(x)...); } }; struct MakeFixPoint { template constexpr auto operator|(F&& f) const { return FixPoint(forward(f)); } }; #define MFP MakeFixPoint()| #define def(name, ...) auto name = MFP [&](auto &&name, __VA_ARGS__) template struct vec_impl { using type = vector::type>; template static type make_v(size_t n, U&&... x) { return type(n, vec_impl::make_v(forward(x)...)); } }; template struct vec_impl { using type = T; static type make_v(T const& x = {}) { return x; } }; template using vec = typename vec_impl::type; template auto make_v(Args&&... args) { return vec_impl::make_v(forward(args)...); } template void quit(T const& x) { cout << x << endl; exit(0); } template constexpr bool chmin(T& x, T const& y) { if (x > y) { x = y; return true; } return false; } template constexpr bool chmax(T& x, T const& y) { if (x < y) { x = y; return true; } return false; } template constexpr auto sumof(It b, It e) { return accumulate(b,e,typename iterator_traits::value_type{}); } template int sz(T const& x) { return x.size(); } template int lbd(C const& v, T const& x) { return lower_bound(v.begin(), v.end(), x)-v.begin(); } template int ubd(C const& v, T const& x) { return upper_bound(v.begin(), v.end(), x)-v.begin(); } // <<< // >>> sieve namespace Sieve { constexpr int MAX = 2e6; vector ps, pf, mu; // primes, min prime factor, mebius auto sieve_init = [](){ pf.resize(MAX+1); iota(pf.begin(), pf.end(), 0); mu.resize(MAX+1,-1); mu[1] = 1; for (int i = 2; i <= MAX; ++i) { if (pf[i] == i) ps.push_back(i); for (int p : ps) { const int x = p*i; if (p > pf[i] || x > MAX) break; pf[x] = p; mu[x] = -mu[i]; if (i%p == 0) mu[x] = 0; } } return 0; }(); bool is_prime(int n) { assert(0 <= n); assert(n <= MAX); return pf[n] == n && n >= 2; } vector > prime_factor(int n) { assert(0 <= n); assert(n <= MAX); vector > ret; while (n > 1) { int p = pf[n], i = 0; while (pf[n] == p) ++i, n /= p; ret.emplace_back(p,i); } return ret; } vector divisors(int n) { assert(0 <= n); assert(n <= MAX); vector ret = {1}; for (auto p : prime_factor(n)) { int m = ret.size(); for (int i = 0; i < m; ++i) { for (int j = 0, v = 1; j < p.second; ++j) { v *= p.first; ret.push_back(ret[i]*v); } } } return ret; } } using namespace Sieve; // <<< int32_t main() { int n; cin >> n; double p; cin >> p; double ans = 0; loop (x,2,<=n) { ans += pow(1-p, divisors(x).size()-2); } cout << ans << endl; }