#include<iostream>

#include<fstream>

using namespace std;
double n,t[10000],s,i;

int main()

{



ifstream cin ("koba.in");

ofstream cout ("koba.out");

cin>>n>>t[1]>>t[2]>>t[3];

t[1]=t[1]%10;

t[2]=t[2]%10;

t[3]=t[3]%10;

s=t[1]+t[2]+t[3];

for(i=4;i<=n;i++)

{

t[i]=t[i-1]+t[i-2]*t[i-3];

t[i]=t[i]%10;

s=s+t[i];

}

cout<<s;

cin.close();

cout.close();

}