#include <fstream>

using namespace std;

ifstream fin ("koba.in");
ofstream fout ("koba.out");

int u (int a)
{
    return a%10;
}

int main()
{
    int n, a, b, c, x, s =0;
    fin >> n >> a >> b >> c;
    a=u(a);
    b=u(b);
    c=u(c);
    s+=a+b+c;
    for (int i =1; i<= n-3; i++)
    {
        x = c + a * b;
        s+=u(x);
        x = u(x);
        a = b;
        b = c;
        c = x;
        //fout << c << '\n';
    }
    fout << s;
    return 0;
}