#include<stdio.h>
FILE *f=fopen("koba.in","r"),
     *g=fopen("koba.out","w");
long i,j,t1,t2,t3,n,k,au;
int main()
{ fscanf(f,"%ld %ld %ld %ld",&n,&t1,&t2,&t3);
  if(n==1) fprintf(g,"%ld\n",t1%10);
  else if(n==2) fprintf(g,"%ld\n",t1+t2%10);
  else if(n==3) fprintf(g,"%ld\n",t1+t2+t3%10);
  else  { n-=3;k=t1%10+t2%10+t3%10;
	  for(i=1;i<=n;++i) au=t1,t1=t2,t2=t3,t3=(au*t1+t2)%10,k+=t3;
	  fprintf(g,"%ld\n",k);}
	  fclose(f);
	  fclose(g);
	  return 0;
}