day0_2

// In this challenge, we practice calculating a weighted mean. //

#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
#include <iomanip>
using namespace std;


int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */ 
    int size, inputValue, inputs;
    vector<int> elements;
    vector<int> weights;
    cin >> size;
    for(int i = 0; i < size; i++){
        cin >> inputValue;
        elements.push_back(inputValue);
    }
    for(int i = 0; i < size; i++){
        cin >> inputValue;
        weights.push_back(inputValue);
    }
    float numerator, denominator;
    for(int i = 0; i < size; i++){
        numerator += elements[i] * weights[i];
        denominator += weights[i];
    }
    cout << fixed << setprecision(1) << numerator / denominator;
    return 0;
}