#include using namespace std; #define all(c) ((c).begin()), ((c).end()) #define dump(c) cerr << "> " << #c << " = " << (c) << endl; #define iter(c) __typeof((c).begin()) #define tr(i, c) for (iter(c) i = (c).begin(); i != (c).end(); i++) #define REP(i, a, b) for (int i = a; i < (int)(b); i++) #define rep(i, n) REP(i, 0, n) #define mp make_pair #define fst first #define snd second #define pb push_back #define debug(fmt, ...) \ fprintf( stderr, \ fmt "\n", \ ##__VA_ARGS__ \ ) typedef unsigned int uint; typedef long long ll; typedef unsigned long long ull; typedef vector vi; typedef vector vll; typedef vector vvll; typedef vector vvi; typedef vector vd; typedef vector vvd; typedef vector vs; typedef pair pii; typedef pair pll; const int INF = 1 << 29; const double EPS = 1e-10; double zero(double d) { return d < EPS ? 0.0 : d; } template bool chmax(T &a, const T &b) { if (a < b) { a = b; return true; } return false; } template bool chmin(T &a, const T &b) { if (b < a) { a = b; return true; } return false; } #define UNIQUE(v) v.erase( unique(v.begin(), v.end()), v.end() ); template ostream &operator<<(ostream &os, const pair &p) { return os << '(' << p.first << ',' << p.second << ')'; } template ostream &operator<<(ostream &os, const vector &a) { os << '['; rep(i, a.size()) os << (i ? " " : "") << a[i]; return os << ']'; } string toString(int i) { stringstream ss; ss << i; return ss.str(); } const int MOD = 1000000007; // a^k ll fpow(ll a, ll k, int M) { ll res = 1ll; ll x = a; while (k != 0) { if ((k & 1) == 1) res = (res * x) % M; x = (x * x) % M; k >>= 1; } return res; } struct prepare { prepare() { cout.setf(ios::fixed, ios::floatfield); cout.precision(8); ios_base::sync_with_stdio(false); } } _prepare; typedef pair data; int main() { int n; cin >> n; vector p(n), q(n); rep(i, n) { double t; cin >> t; p[i] = t / 1000; } rep(i, n) { double t; cin >> t; q[i] = t / 100; } priority_queue que; rep(i, n) que.push(mp(p[i] * q[i], i)); double ans = 0.0; REP(_t, 1, (int) (1e6)) { data d = que.top(); que.pop(); double prob = d.first; int i = d.second; ans += prob * _t; que.push(mp(prob * (1.0 - q[i]), i)); } cout << ans << endl; return 0; }