#include <fstream>
#include <cstring>

using namespace std;

ifstream cin("cifra.in");
ofstream cout("cifra.out");

int main()
{
    string sr;
    cin >> sr;
    if ( sr.length() < 2 )
    {
        int p = sr[0] - 48;
        int s = 0;
        if ( p == 0 )
            s += 0;
        else if ( p == 1 )
            s += 1;
        else if ( p == 2 )
            s += 5;
        else if ( p == 3 )
            s += 2;
        else if ( p == 4 )
            s += 8;
        else if ( p == 5 )
            s += 3;
        else if ( p == 6 )
            s += 9;
        else if ( p == 7 )
            s += 2;
        else if ( p == 8 )
            s += 8;
        else if ( p == 9 )
            s += 7;
        cout << s % 10;
    }
    else
    {
        int p = ( sr[sr.length() - 2] - 48 ) * 10 + sr[sr.length() - 1] - 48;
        int s = p / 20 * 4;
        p = p % 20;
        if ( p == 0 )
            s += 0;
        else if ( p == 1 )
            s += 1;
        else if ( p == 2 )
            s += 5;
        else if ( p == 3 )
            s += 2;
        else if ( p == 4 )
            s += 8;
        else if ( p == 5 )
            s += 3;
        else if ( p == 6 )
            s += 9;
        else if ( p == 7 )
            s += 2;
        else if ( p == 8 )
            s += 8;
        else if ( p == 9 )
            s += 7;
        else if ( p == 10 )
            s += 7;
        else if ( p == 11 )
            s += 8;
        else if ( p == 12 )
            s += 4;
        else if ( p == 13 )
            s += 7;
        else if ( p == 14 )
            s += 3;
        else if ( p == 15 )
            s += 8;
        else if ( p == 16 )
            s += 4;
        else if ( p == 17 )
            s += 1;
        else if ( p == 18 )
            s += 5;
        else if ( p == 19 )
            s += 4;
        cout << s % 10;
    }
    return 0;
}