#include <fstream>

using namespace std;
ifstream fin("koba.in");
ofstream fout("koba.out");
int n,t1,t2,t3,s,aux;
int main()
{
    fin>>n;
    fin>>t1>>t2>>t3;
    t1=t1%10;
    t2=t2%10;
    t3=t3%10;
    if(n==1)
    {
        fout<<t1;
        return 0;
    }
    else if(n==2)
    {
        fout<<t1+t2;
        return 0;
    }
    else if(n==3)
    {
        fout<<t1+t2+t3;
        return 0;
    }
    s=t1+t2+t3;
    for(int i=4;i<=n;i++)
    {
        aux=t3;
        t3=t3+t2*t1;
        t1=t2;
        t2=aux;
        t3%=10;
        s+=t3;
    }
    fout<<s;
    return 0;
}