#include <stdio.h>
#define input "koba.in"
#define output "koba.out"
int t1,t2,t3,n,i;
long sol;
void citire()
{
 FILE *fin;
 fin=fopen(input,"r");
 fscanf(fin,"%d %d %d %d",&n,&t1,&t2,&t3);
 fclose(fin);
}
void solve()
{
 int nr;
 sol=0;
 t1%=10;
 t2%=10;
 t3%=10;
 if (n==1) sol=t1;
    else
 if (n==2) sol=t1+t2;
    else
 if (n==3) sol=t1+t2+t3;
    else
    {
     sol=t1+t2+t3;
     for (i=4;i<=n;i++)
	 {
	  nr=(t3+t2*t1)%10;
	  t1=t2;
	  t2=t3;
	  t3=nr;
	  sol+=nr;
	 }
    }
}
void afisare()
{
 FILE *fout;
 fout=fopen(output,"w");
 fprintf(fout,"%ld",sol);
 fclose(fout);
}
int main()
{
 citire();
 solve();
 afisare();
 return 0;
}