#include using namespace std; #define repl(i,a,b) for(int i=(int)(a);i<(int)(b);i++) #define rep(i,n) repl(i,0,n) #define mp(a,b) make_pair((a),(b)) #define pb(a) push_back((a)) #define all(x) (x).begin(),(x).end() #define uniq(x) sort(all(x)),(x).erase(unique(all(x)),end(x)) #define fi first #define se second #define dbg(x) cout<<#x" = "<<((x))< ostream& operator<<(ostream& o, const pair &p){o<<"("< ostream& operator<<(ostream& o, const vector &v){o<<"[";for(T t:v){o<>n>>p; vector vec(n+1, 1); // 残っている確率 double ans = 0; for(int i=2; i<=n; i++){ ans += vec[i]; for(int j=2*i; j<=n; j+=i) vec[j] *= (1.0-p); } printf("%.8f\n", ans); return 0; }