#include <iostream>
#include <stdlib.h>
using namespace std;
int putere(int numarul)
{
    int p=1;
    for(int i=1; i<=numarul; i++)
    {
		numarul=numarul%10;
        p=p*numarul;
        p=p%10;
    }
    return p;
}
int main()
{
    freopen("cifra.in","r+", stdin);
    freopen("cifra.out", "w", stdout);
     
    int s=0, n, cif;
    int sir[100];
	char ch[10];
	ch[0]='\0';
    cin>>n;
    for(int i=1; i<=n; i++)
	{
		cin>>ch;
        sir[i]=atoi(ch);
	}
    for(int j=1; j<=n; j++)
    {

        s=s+putere(sir[j]);
        cif=s%10;
        
    }
	cout<<cif<<endl;
return 0;
}