#include <iostream>
#include <iomanip>
 
using namespace std;
 
int main() {
    int n;
    cin >> n;  // first number is the count of following numbers
 
    int sum = 0;          // FOO: sum of numbers read so far
    int cnt = 0;          // BAR: count of numbers read so far
    int best_sum = 0;     // BAZ: best sum found
    int best_cnt = 1;     // QUZ: best count found
 
    for (int i = 0; i < n; ++i) {
        int x;
        cin >> x;
        sum += x;
        ++cnt;
        // Compare sum/cnt with best_sum/best_cnt using cross multiplication
        if (sum * best_cnt >= cnt * best_sum) {
            best_sum = sum;
            best_cnt = cnt;
        }
    }
 
    double result = static_cast<double>(best_sum) / best_cnt;
    cout << fixed << setprecision(6) << result << endl;
 
    return 0;
}