#include "bits/stdc++.h"
using namespace std;
#define FOR(i,j,k) for(int (i)=(j);(i)<(int)(k);++(i))
#define rep(i,j) FOR(i,0,j)
#define each(x,y) for(auto &(x):(y))
#define mp make_pair
#define MT make_tuple
#define all(x) (x).begin(),(x).end()
#define debug(x) cout<<#x<<": "<<(x)<<endl
#define smax(x,y) (x)=max((x),(y))
#define smin(x,y) (x)=min((x),(y))
#define MEM(x,y) memset((x),(y),sizeof (x))
#define sz(x) (int)(x).size()
#define rt return
using dbl = double;
using ll = long long;
using pii = pair<int, int>;
using vi = vector<int>;
using vll = vector<ll>;

double F(int n) {
    double a = 1, b = 1, aa = 0, bb = 0;
    for (int i = 1; i <= n; ++i) {
        a *= 0.81;
        b *= 0.9;
        aa += a;
        bb += b;
    }
    return sqrt(aa) / bb;
}

double f(int n) {
    return (F(n) - F(100000)) / (F(1)-F(100000)) * 1200.0;
}

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

double rg(double x) {
    return 800 * log(x) / log(2);
}

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

    int N;
    cin >> N;
    vector<dbl> RPerf(N + 1);
    FOR(i, 1, N + 1)cin >> RPerf[i];

    dbl a = 0, b = 0, p = 1;
    FOR(i, 1, N + 1) {
        p *= 0.9;
        a += g(RPerf[i])*p;
        b += p;
    }
    dbl rating = rg(a / b) - f(N);
    cout << (ll)rating << endl;
}