////////////////////////////// // Check before you submit. // #define _ATCODER_LIBRARY const long long MOD = 1e9+7; // const long long MOD = 998244353; ///////////////////////////// #include using namespace std; #include using namespace boost::multiprecision; #ifdef _ATCODER_LIBRARY #include using namespace atcoder; #endif // _ATCODER_LIBRARY const long long INF = 1LL << 60; const double PI = acos(-1); using ll = long long; using P = pair; #define FOR(i,a,b) for (ll i=(a);i<(ll)(b);++i) #define REP(i,n) FOR(i,0,n) #define ALL(v) (v).begin(),(v).end() #define SUM(v) accumulate(ALL(v),0ll) templateistream& operator>>(istream&i,vector&v){REP(j,v.size())i>>v[j];return i;} templatestring join(vector&v){stringstream s;REP(i,v.size())s<<' '<ostream& operator<<(ostream&o,vector&v){if(v.size())o<string join(vector>&vv){string s="\n";REP(i,vv.size())s+=join(vv[i])+"\n";return s;} templateostream& operator<<(ostream&o,vector>&vv){if(vv.size())o<istream& operator>>(istream&i,pair&v){return i>>v.first>>v.second;} templateostream& operator<<(ostream&o,pair&v){return o<T up(T a, T b){assert(b);return (a+b-1)/b;} templatebool eq(A const&... a){auto t={a...};assert(t.size());auto tar=*t.begin();for(const auto&e:t)if(tar!=e)return false;return true;} templatebool chmin(T &a, T b){if(a>b){a=b;return false;}return true;} templatebool chmax(T &a, T b){if(abool chmax(T &a, initializer_listl){return chmax(a,max(l));} templatebool chmin(T &a, initializer_listl){return chmin(a,min(l));} ////////////////////////////////////////////////////////////////// // My Library ////////////////////////////////////////////////////////////////// ////////////////////////////////////////////////////////////////// // Contest Code ////////////////////////////////////////////////////////////////// int main(int argc, char **argv) { init_init_init(); ll N; cin >> N; double p; cin >> p; vector pow(N); pow[0] = 1.f; REP(i, N-1) pow[i+1] = pow[i]*(1-p); DEBUG(pow[1]); vector div_cnt(N+1, 0ll); double res{0.f}; for (ll x = 2; x <= N; ++x) { for (ll m = x; m <= N; m += x) div_cnt[m]++; DEBUG(div_cnt[x]); res += pow[div_cnt[x]-1]; } std::cout << res << std::endl; }