#include "bits/stdc++.h"

#define REP(i,n) for(ll i=0;i<n;++i)
#define RREP(i,n) for(ll i=n-1;i>=0;--i)
#define FOR(i,m,n) for(ll i=m;i<n;++i)
#define RFOR(i,m,n) for(ll i=n-1;i>=m;--i)
#define ALL(v) (v).begin(),(v).end()
#define UNIQUE(v) v.erase(unique(ALL(v)),v.end());
#define DUMP(v) REP(aa, (v).size()) { cout << v[aa]; if (aa != v.size() - 1)cout << " "; else cout << endl; }
#define INF 1000000001ll
#define MOD 1000000007ll
#define EPS 1e-9

const int dx[8] = { 1,1,0,-1,-1,-1,0,1 };
const int dy[8] = { 0,1,1,1,0,-1,-1,-1 };


using namespace std;
typedef long long ll;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef vector<vi> vvi;
typedef vector<vl> vvl;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
ll max(ll a, int b) { return max(a, ll(b)); }
ll max(int a, ll b) { return max(ll(a), b); }
ll min(ll a, int b) { return min(a, ll(b)); }
ll min(int a, ll b) { return min(ll(a), b); }
///(´・ω・`)(´・ω・`)(´・ω・`)(´・ω・`)(´・ω・`)(´・ω・`)///

double sum(double x, int n) {
	return x*(1 - pow(x, n)) / (1 - x);
}
double F(int n) {
	if (n == INF) {
		return 0.1 / sqrt(0.19);
	}
	return sqrt(sum(0.81, n)) / sum(0.9, n);
}
double f(int n) {
	return (F(n) - F(INF)) / (F(1) - F(INF)) * 1200;
}
double g(double x) {
	return pow(2, x / 800);
}
double invg(double x) {
	return 800 * log2(x);
}
int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);
	int n;
	cin >> n;
	vi v(n);
	REP(i, n)cin >> v[i];
	double tmp = 0;
	REP(i, n)tmp += g(v[i]) * pow(0.9,i + 1);
	int rating = invg(tmp / sum(0.9, n)) - f(n);
	cout << rating << endl;
}