#include<fstream>
using namespace std;
ifstream f("koba.in");
ofstream g("koba.out");
int n,t1,t2,t3,t4,i,s;
int main()
{f>>n>>t1>>t2>>t3;
t1=t1%10;
t2=t2%10;
t3=t3%10;
s=t1+t2+t3;
if(n==1)
	s=t1;
else 
	if(n==2)
		s=t1+t2;
	else 
		if(n==3) 
			s=t1+t2+t3;
else
for(i=4;i<=n;i++)
{t4=(t3+t2*t1)%10;
t1=t2%10;
t2=t3%10;
t3=t4%10;
s=s+t4;
}
g<<s<<'\n';
f.close();
g.close();
return 0;
}