#include <fstream>
using namespace std;
ifstream fin("koba.in");
ofstream fout("koba.out");

int uc,scif,x,y,z,n,i,tnou;

int main()
{
    fin>>n>>x>>y>>z;

    for(i=1;i<=n;i++)
    {
        x=x%10;
        y=y%10;
        z=z%10;
        tnou=z+y*x;
        x=y;
        y=z;
        z=tnou;
        scif=scif+tnou%10;
    }
        fout<<scif;


    return 0;
}