#include<fstream>

using namespace std;

ifstream fin ("koba.in");
ofstream fout ("koba.out");
int main ()
{
    int n,i;
    fin>>n;
    long long unsigned s;
    long long unsigned a[n+5];
    fin>>a[1]>>a[2]>>a[3];
    s=a[1]%10+a[2]%10+a[3]%10;
    for(i=3;i<n;i++)
    {
    a[i+1]=a[i]+a[i-1]*a[i-2];
    a[i+1]%=10;
    s+=a[i+1];
}//s=0;
//for(i=1;i<=n;i++)
//s+=(a[i]%10);
fout<<s;
return 0;
}