#include "bits/stdc++.h"
using namespace std;
#define int long long
#define FOR(i, a, b) for(int i=(a);i<(b);i++)
#define RFOR(i, a, b) for(int i=(b-1);i>=(a);i--)
#define REP(i, n) for(int i=0; i<(n); i++)
#define RREP(i, n) for(int i=(n-1); i>=0; i--)
#define ALL(a) (a).begin(),(a).end()
#define UNIQUE_SORT(l) sort(ALL(l)); l.erase(unique(ALL(l)), l.end());
#define CONTAIN(a, b) find(ALL(a), (b)) != (a).end()
#define array2(type, x, y) array<array<type, y>, x>
#define vector2(type) vector<vector<type> >
#define out(...) printf(__VA_ARGS__)

int dxy[] = {0, 1, 0, -1, 0};

void solve();
signed main()
{
#if DEBUG
    std::ifstream in("input.txt");
    std::cin.rdbuf(in.rdbuf());
#endif
    cin.tie(0);
    ios::sync_with_stdio(false);
    solve();
    return 0;
}

/*================================*/

int N,M,Q;
int P[100];

double F(double n) {
    double a = 0;
    double b = 0;
    REP(i,n) {
        a += pow(0.81, i+1);
        b += pow(0.9, i+1);
    }
    return sqrt(a)/b;
}

double f(double n) {
    double a = F(n) - F(1e6);
    double b = F(1) - F(1e6);
    return 1200 * a / b;
}

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

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

void solve() {
    cin>>N;
    REP(i,N)cin>>P[i];
    
    double a = 0;
    double b = 0;
    REP(i,N) {
        a += g(P[i])*pow(0.9, i+1);
        b += pow(0.9, i+1);
    }
    double ans = invg(a/b)-f(N);
    
    cout << round(ans) << endl;
}