#include<stdio.h>
long j,r,num,nn,n,t1,t2,t3,c,s,sum,k,x[10000];
int main()
{
	freopen("koba.in","r",stdin);
	freopen("koba.out","w",stdout);

	scanf("%ld",&n);
	scanf("%ld %ld %ld",&t1,&t2,&t3);
	s=(t1%10+t2%10+t3%10);
	n=n-3;
	nn=n;
	while(n)
	{
		c=s;
		s+=(t3%10+((t2%10)*(t1%10))%10)%10;
		t1=t2%10;
		t2=t3%10;
		t3=(s-c)%10;
		if(t3==0&&k==0)
			{
				k=1;
				num++;
				x[num]=t3;
				sum+=t3;
			}
		else
		 if(t3==0&&k==1)
			break;
			else
			if(k==1)
				{
				 num++;
				x[num]=t3;
				sum+=t3;
				}
		n--;
	}
	if(num)
	{
	r=(n)/num;
	s+=sum*r;
	r=(n)%num;
	for(j=1;j<=r;++j)
		s+=x[j];
	}
	printf("%ld",s);
	return 0;
}