#include <fstream>
#include<cmath>

using namespace std;
ifstream in("cifra.in");
ofstream out("cifra.out");
int main()
{
    int n,i,s=0;
    in>>n;
    for(i=1;i<=n;i++)
        s=s+pow(i,i);
        out<<s%10;
    return 0;
}