#include <bits/stdc++.h>

using namespace std;

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

int n, t1, t2, t3;
long long s = 0;

int main()
{
    fin>>n>>t1>>t2>>t3;

    t1 %=10;
    t2 %=10;
    t3 %=10;

    s += t1+t2+t3;

    while(n>3)
    {
        n--;
        int aux = ( t3 + t2 * t1 ) %10;
        s += aux;
        t1 = t2;
        t2 = t3;
        t3 = aux;
    }
    fout<<s;
}