#include <bits/stdc++.h>
using namespace std;

using ll = long long;
using ull = unsigned long long;
using ld = long double;
template<class t> using vc = vector<t>;
template<class t> using vvc = vc<vc<t>>;
using pi = pair<int,int>;
using vi = vc<int>;
using vvi = vvc<int>;

#define rep(i,a,b) for (int i = a; i < b; i++)
#define irep(i,a,b) for (int i = a; i > b; i--)
#define print(n) cout << n << '\n'
#define pritn(n) print(n)
#define rup(a,b) (a+b-1)/b
#define input(A,N) rep(i,0,N) cin>>A[i];

ld F(ld n){
    if (n == -1){
        ld ans = sqrt(0.81/(1-0.81));
        ans /= (0.9/(1-0.9));
        return ans;
    }
    ld ans = 0;
    ld now = 1;
    rep(i,0,n){
        now *= 0.81;
        ans += now;
    }
    ans = sqrt(ans);
    ld nn = 0;
    now = 1;
    rep(i,0,n){
        now *= 0.9;
        nn += now;
    }
    ans/= nn;
    return ans;
}

ld f(ld n){
    ld ans = 1200;
    ans *= (F(n)-F(-1));
    ans /= (F(1)-F(-1));
    return ans;
}

ld g(ld n){
    return pow(2,n/800);
}
ld gi(ld x){
    return 800*log2l(x);
}


int main(){
    cout << fixed << setprecision(15);
    
    int N;
    cin >> N;
    vc<ld> p(N);
    input(p,N);
    ld ans = 0;
    ld now = 1;
    ld n = 0;
    rep(i,0,N){
        now *= 0.9;
        ans += g(p[i])*now;
        n += now;
    }
    ans /= n;
    ans = gi(ans);
    ans -= f(N);
    print(ll(ans));

    //system("pause");
    return 0;
}