#include <bits/stdc++.h>   #pragma comment(linker,  /STACK:256000000 )   using namespace std;   const long long inf = 1e18;   const double eps = 1e-9;   const double pi = 4 * atan(1.0);   const int N = int(2e5) + 100;   const int ITERS = 80;   int m;   pair<int, int> a[N];   vector<pair<int, int> > group[N];   long long sum_t[N];   int p[N];   double fen_suff[N];   inline long long val(const pair<int, int>& a, const pair<int, int>& b) {     return 1LL * a.first * b.second - 1LL * b.first * a.second;   }   inline bool cmp(const pair<int, int>& a, const pair<int, int>& b) {     return val(a, b) > 0;   }   inline void add_suff(int cp, double val) {     int pos = lower_bound(p, p + m, cp) - p;     assert(pos < m && p[pos] == cp);     while (pos >= 0) {       if (val < fen_suff[pos]) {         fen_suff[pos] = val;       } else {         break;       }       pos = (pos & (pos + 1)) - 1;     }   }   inline double get_suff(int cp) {     int pos = lower_bound(p, p + m, cp) - p;     assert(pos < m && p[pos] == cp);     double res = 1e100;     ++pos;     while (pos < m) {       res = min(res, fen_suff[pos]);       pos = (pos | (pos + 1));     }     return res;   }   int main() {     int n;     cin >> n;     for (int i = 0; i < n; ++i) {       scanf( %d , &a[i].first);     }     for (int i = 0; i < n; ++i) {       scanf( %d , &a[i].second);     }     sort(a, a + n, cmp);     for (int i = 0; i < n; ++i) {       p[i] = a[i].first;     }     sort(p, p + n);     m = unique(p, p + n) - p;     int i = 0, sz = 0;     while (i < n) {       int j = i;       while (j + 1 < n && val(a[i], a[j + 1]) == 0) {         ++j;       }       for (int z = i; z <= j; ++z) {         group[sz].push_back(a[z]);       }       sort((group[sz]).begin(), (group[sz]).end());       ++sz;       i = j + 1;     }     for (int i = 0; i < sz; ++i) {       if (i > 0) {         sum_t[i] += sum_t[i - 1];       }       for (pair<int, int> p : group[i]) {         sum_t[i] += p.second;       }     }     double l = 0, r = 1;     for (int it = 0; it < ITERS; ++it) {       double mid = (l + r) / 2;       for (int i = 0; i < m; ++i) {         fen_suff[i] = 1e100;       }       bool fl = false;       for (int i = sz - 1; i >= 0 && !fl; --i) {         int ptr = ((int)(group[i]).size()) - 1;         for (int j = ((int)(group[i]).size()) - 1; j >= 0; --j) {           while (group[i][ptr].first > group[i][j].first) {             add_suff(                 group[i][ptr].first,                 group[i][ptr].first * (1.0 - mid * sum_t[i] / sum_t[sz - 1]));             --ptr;           }           if (group[i][j].first *                   (1.0 - mid * ((i > 0 ? sum_t[i - 1] : 0) + group[i][j].second) /                              sum_t[sz - 1]) >               get_suff(group[i][j].first)) {             fl = true;             break;           }         }         while (ptr >= 0) {           add_suff(group[i][ptr].first,                    group[i][ptr].first * (1.0 - mid * sum_t[i] / sum_t[sz - 1]));           --ptr;         }       }       if (fl) {         r = mid;         continue;       }       for (int i = 0; i < m; ++i) {         fen_suff[i] = 1e100;       }       for (int i = 0; i < sz && !fl; ++i) {         int ptr = ((int)(group[i]).size()) - 1;         for (int j = ((int)(group[i]).size()) - 1; j >= 0; --j) {           while (group[i][ptr].first > group[i][j].first) {             add_suff(                 group[i][ptr].first,                 group[i][ptr].first * (1.0 - mid * sum_t[i] / sum_t[sz - 1]));             --ptr;           }           if (group[i][j].first *                   (1.0 - mid * ((i > 0 ? sum_t[i - 1] : 0) + group[i][j].second) /                              sum_t[sz - 1]) >               get_suff(group[i][j].first)) {             fl = true;             break;           }         }         while (ptr >= 0) {           add_suff(group[i][ptr].first,                    group[i][ptr].first * (1.0 - mid * sum_t[i] / sum_t[sz - 1]));           --ptr;         }       }       if (fl) {         r = mid;       } else {         l = mid;       }     }     printf( %.18lf n , (l + r) / 2);     return 0;   }