#include "bits/stdc++.h"
#define REP(i,n,N) for(int i=(n); i<(N); i++)
#define RREP(i,n,N) for(ll i=(N-1); i>=n; i--)
#define CK(n,a,b) ((a)<=(n)&&(n)<(b))
#define ALL(v) (v).begin(),(v).end()
#define p(s) cout<<(s)<<endl
#define p2(a,b) cout<<(a)<<" "<<(b)<<endl
#define v2(T) vector<vector<T>>
typedef long long ll;
using namespace std;
const ll inf=1e18;

int N, RPerf[101];
double finf = 0;
double g(double x) { return pow(2, x / 800); }
double gg(double x) { return 800 * log2(x); }

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

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

double rating(int n) {
    double up = 0, dn = 0;
    REP(i, 0, n) up += g(RPerf[i]) * pow(0.9, i + 1);
    REP(i, 0, n) dn += pow(0.9, i + 1);

    return gg(up / dn) - f(n);
}

int main() {
    int n;
    cin>>n;
    REP(i, 0, n) cin>>RPerf[i];
    finf = 1/sqrt(19);
    int ans=ceil(rating(n));
    p(ans);
    return 0;
}