#include <bits/stdc++.h>
using namespace std;
using i64 = int64_t;
using vi = vector<i64>;
using vvi = vector<vi>;

double F[101];
double f[101];

void build() {
    double sum1 = 0, sum2 = 0;
    for (int i = 1; i <= 100; i++) {
        sum1 += pow(0.81, i);
        sum2 += pow(0.9, i);
        F[i] = sqrt(sum1) / sum2;
        // cout << sqrt(sum1) / sum2 << endl;
    }
    double Finf = 0.22941573387056196642;
    for (int i = 1; i <= 100; i++) {
        f[i] = (F[i] - Finf) / (F[1] - Finf) * 1200;
    }
}

double ginv(double y) {
    return log2(y) * 800;
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);
    cout.setf(ios::fixed);
    cout.precision(20);
    build();

    int n;
    cin >> n;
    vi rs(n);
    for (int i = 0; i < n; i++) {
        cin >> rs[i];
    }

    double sum = 0, sum2;
    for (int i = 1; i <= n; i++) {
        sum += pow(2, rs[i - 1] / 800.0) * pow(0.9, i);
        sum2 += pow(0.9, i);
    }
    double rating = ginv(sum / sum2) - f[n];
    // cout << rating << endl;
    cout << i64(rating + 0.5) << endl;
}