#include <bits/stdc++.h>
#define L long long
#define Lq multiset<int>::iterator
using namespace std;
ifstream in("koba.in");
ofstream out("koba.out");
int n,a,b,c,d,s;
int main()
{
    in>>n>>a>>b>>c;
    a%=10,b%=10,c%=10;
    s=a%10+b%10+c%10;
    for(int i=4;i<=n;++i)
    {
        d=(c+b*a)%10;
        s+=d;
        a=b,b=c,c=d;
    }
    out<<s;
}