#define _CRT_SECURE_NO_WARNINGS
#include<iostream>
#include<sstream>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<climits>
#include<cmath>
#include<string>
#include<vector>
#include<set>
#include<map>
#include<queue>
#include<numeric>
#include<functional>
#include<algorithm>
#include<bitset>
#include<tuple>
#include<unordered_set>
#include<random>
#include<array>
#include<cassert>
using namespace std;
#define INF (1<<29)
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define all(v) v.begin(),v.end()
#define uniq(v) v.erase(unique(all(v)),v.end())



double F(int n){
	return sqrt(0.81 * (1 - pow(0.81,n)) /(1-0.81) ) 
		/ ( 0.9*(1- pow(0.9,n)) / (1 - 0.9));
}

double Finf = sqrt(0.81 / (1 - 0.81)) / (0.9 / (1 - 0.9));

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

double g(double x){
	return pow(2.0 , x/800);
}

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



int main() {
	ios::sync_with_stdio(0);
	cin.tie(0);

	

	int n;
	cin>>n;
	double s= 0, t=0;
	int perf[100];

	rep(i,n){
		cin>>perf[i];

		s += g(perf[i]) * pow(0.9, i+1);
	}
	rep(i, n){
		t += pow(0.9, i+1);
	}

	cout << static_cast<int>(ginv(s / t) - f(n))<<endl;

	
	return 0;
}