#define _USE_MATH_DEFINES
#include <cstdio>
#include <iostream>
#include <sstream>
#include <fstream>
#include <iomanip>
#include <algorithm>
#include <cmath>
#include <complex>
#include <string>
#include <vector>
#include <list>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <bitset>
#include <numeric>
#include <limits>
#include <climits>
#include <cfloat>
#include <functional>
#include <iterator>
using namespace std;

// 初項r、公比r、長さnの等比級数
double geometricSeries(double r, int n)
{
    return r * (1 - pow(r, n)) / (1 - r);
}

// 初項r、公比rの無限等比級数
double infiniteGeometricSeries(double r)
{
    return r / (1.0 - r);
}

double F(int n)
{
    double a = geometricSeries(0.81, n);
    double b = geometricSeries(0.9, n);
    return sqrt(a) / b;
}

double f(int n)
{
    double a = infiniteGeometricSeries(0.81);
    double b = infiniteGeometricSeries(0.9);
    double c = sqrt(a) / b;
    return (F(n) - c) / (F(1) - c) * 1200;
}

double g(double x)
{
    return pow(2.0, x / 800.0);
}

double g_inv(double x)
{
    return 800.0 * log(x) / log(2);
}

double solve(const vector<int>& v)
{
    int n = v.size();
    double x = 0.0;
    for(int i=n-1; i>=0; --i){
        x += g(v[i]);
        x *= 0.9;
    }
    x /= geometricSeries(0.9, n);
    return g_inv(x) - f(n);
}

int main()
{
    int n;
    cin >> n;
    vector<int> v(n);
    for(int i=0; i<n; ++i)
        cin >> v[i];

    int ans = (int)round(solve(v));
    cout << ans << endl;

    return 0;
}