#include<fstream.h>
#include<math.h>

int main()
{
	ifstream fin("cifra.in");
	ofstream fout("cifra.out");
	long n,t;
	fin>>t;
	long i=0,j=0,s=0;
	for (i=0;i<t;i++)
	{
		fin>>n;
		for (j=1;j<=n;j++)
		{
		int a,b;
		a=j%10;
		if (j>10)
		b=(j%100)%4;
		else
		b=j%4;
		if ( b!=0) 
		s=s+pow(a;b);
		if (b==0)
		s=s+pow(a;4);
		s=s%10;
		}
	}
	fout<<s;
	fin.close();
	fout.close();
	return 0;
}