#include <fstream>
#include <iostream>
using namespace std;
ifstream in("cifra.in");
ofstream out("cifra.out");
int main()
{
    int i,z,c,a,n,S=0,u;
    cout<<"n= ";
    cin>>n;
    in>>n;
    for(i=1;i<=n;i++)
    {
          a=1;
        for(c=1;c<=i;c++)
            a*=i;
        S+=a;
        u=S%10;
    }
    out<<S%10;
    cout<<S%10;
    //cout<<"S= "<<S;
    return 0;
}