#include <fstream.h>
#include <math.h>
long n,t,ucifs,sucif,i,ucifi,ucifnr,c;
unsigned long nrcurent;
ifstream fin("cifra.in");
ofstream fout("cifra.out");
int main()
{
	fin>>t;
	for (c=1;c<=t;c++)
	{
		fin>>n;
		sucif=0;
		for(i=1;i<=n;i++)
		{
			ucifi=i%10;
			nrcurent=(unsigned long)pow(ucifi,i);
			ucifnr=nrcurent%10;
			sucif=sucif+ucifnr;
		}
		ucifs=sucif%10;
	}
	fout<<ucifs<<"\n";
	return 0;
}