#include <iostream>
#include <fstream>
#include <cmath>
#include <string.h>

using namespace std;

int main()
{
        ifstream f("cifra.in");
        ofstream g("cifra.out");

    long t,i ;
    f >> t ;

    char	numar[102];
	char last,l1;
	short c;

     long long suma = 0 ;
     f.get();
      for (i=1;i<=t;i++)

      {   f.get(numar,102);f.get();
            c=numar[strlen(numar)-1]-48;
          suma += (int)pow(c,c)%10;
          suma = suma % 10 ;
      }

            g<<suma;

    f.close();
    g.close();
    return 0;
}