#include <fstream>
using namespace std;
ifstream fin("cifra.in");
ofstream fout("cifra.out");
int n,i,j,s,p;
int main()
{
    fin>>n;
    for(i=1;i<=n;i++)
    {
        p=1;
        for(j=1;j<=i;j++)
            p=p*i;
        s=s+p;
    }
    fout<<s%10;
    return 0;
}