#include<cstdio>
#include<vector>
#include<cmath>


using namespace std;
using vi=vector<int>;


double F_inf;


double F(int n)
{
	double u=0.0, l=0.0;
	double tu=1.0, tl=1.0;

	for(int i=0;i<n;i++)
	{
		tu*=0.81;
		tl*=0.9;
		u+=tu;
		l+=tl;
	}
	return sqrt(u)/l;
}


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


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


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


int main(void)
{
	int n;

	F_inf=F(10000);
	while(scanf("%d", &n)==1)
	{
		vi a(n);

		for(int i=0;i<n;i++)
		{
			scanf("%d", &a[i]);
		}

		double u=0.0, l=0.0, t=1.0;
		for(int i=0;i<n;i++)
		{
			t*=0.9;
			u+=g(a[i])*t;
			l+=t;
		}
		printf("%.0f\n", g_inv(u/l)-f(n));
	}

	return 0;
}