#include<stdio.h>
int t1,t2,t3,t4;
long n,k;
int main()
{
	long i;
	freopen("koba.in","r",stdin);
	freopen("koba.out","w",stdout);
	scanf("%ld %d %d %d",&n,&t1,&t2,&t3);
	t1=t1%10;
	t2=t2%10;
	t3=t3%10;
	k=t1+t2+t3;
	i=4;
	while(i<=n){
		t4=(t3+(t1*t2)%10)%10;
		k+=t4;
		t3=t4;
		t2=t3;
		t1=t2;
		++i;
	}
	printf("%ld\n",k);
	return 0;
}