#include <fstream>
using namespace std;
ifstream fin("koba.in");
ofstream fout("koba.out");
int t1,t2,t3,n,t4;
long long s;
int main()
{
    fin>>n>>t1>>t2>>t3;
    t1%=10;
    t2%=10;
    t3%=10;
    s=t3+t2+t1;
    for(int i=4;i<=n;i++)
    {
        t4=t3+t2*t1;
        t4%=10;
        s+=t4;
        t1=t2;
        t2=t3;
        t3=t4;
    }
    fout<<s;
    return 0;
}