#include using namespace std; typedef long long ll; typedef pair p_ll; template void debug(T itr1, T itr2) { auto now = itr1; while(now=0; i--) const ll MOD = pow(10,9)+7; const ll LLINF = pow(2,61)-1; const int INF = pow(2,30)-1; vector fac; void c_fac(int x=pow(10,6)+10) { fac.resize(x,true); rep(i,x) fac[i] = i ? (fac[i-1]*i)%MOD : 1; } ll inv(ll a, ll m=MOD) { ll b = m, x = 1, y = 0; while (b!=0) { int d = a/b; a -= b*d; swap(a,b); x -= y*d; swap(x,y); } return (x+m)%m; } ll nck(ll n, ll k) { return fac[n]*inv(fac[k]*fac[n-k]%MOD)%MOD; } ll gcd(ll a, ll b) { if (a (const room &x) const { return p*q>x.p*x.q||(p*q==x.p*x.q&&p>x.p); }; bool operator< (const room &x) const { return p*q> n; double p[n]; rep(i,n) { cin >> p[i]; p[i]/=1000; } double q[n]; rep(i,n) { cin >> q[i]; q[i]/=100; } priority_queue pq; rep(i,n) pq.push({p[i],q[i]}); double result = 0, np = 1, nall = 1; rep(i,1000000) { room now = pq.top(); pq.pop(); // cout << np << " " << now.q << " " << result << endl; result += (i+1) * now.p * np / nall * now.q; np -= now.p*now.q; nall -= now.p * now.q; now.p -= now.p * now.q; pq.push(now); } cout << setprecision(10) << result << endl; return 0; }