#include <bits/stdc++.h>
using namespace std;

int N;
int RPerf[100];

double g(double x) {
  return pow(2, x / 800);
}

double inv_g(double x) {
  return 800 * log2(x);
}

double F(int n) {
  double u = 0, v = 0;
  for (int i = 0; i < n; ++i) {
    u += pow(0.81, i + 1);
    v += pow(0.9, i + 1);
  }
  return sqrt(u) / v;
}

double f(int n) {
  return (F(n) - F(int(5e6))) / (F(1) - F(int(5e6))) * 1200;
}

double r(int n) {
  double u = 0, v = 0;
  for (int i = 0; i < n; ++i) {
    u += g(RPerf[i]) * pow(0.9, i + 1);
    v += pow(0.9, i + 1);
  }
  return inv_g(u / v) - f(n);
}

int main() {
  cin >> N;
  for (int i = 0; i < N; ++i) {
    cin >> RPerf[i];
  }
  cout << ceil(r(N) + 0.5) << endl;
  return 0;
}