#include<fstream>
using namespace std;
int n,t1,t2,t3,c,i,s;
int main()
{
    ifstream f("koba.in");
    ofstream g("koba.out");
    f>>n>>t1>>t2>>t3;
    t1=t1%10;
    t2=t2%10;
    t3=t3%10;
    s=t1+t2+t3;
    for(i=4;i<=n;i++)
    {
        c=t3;
        t3=(t3+t2*t1)%10;
        s+=t3;
        t1=t2;
        t2=c;
    }
    g<<s;
}