#include <stdio.h>
int n, f1, f2, f3, f4, s;

int main()
{
	freopen("koba.in","r",stdin);
	freopen("koba.out","w",stdout);
	scanf("%d %d %d %d", &n, &f1, &f2, &f3);
	if (n == 1){ printf("%d\n",f1%10); return 0;}
	if (n == 2){ printf("%d\n",(f1 % 10) + (f2 % 10)); return 0;}
	s = (f1 % 10) + (f2 % 10) + (f3 % 10) ;
	int i;
	for (i = 4; i <= n; i++)
	{
		f4 = (f3 + (f2 * f1) % 10) % 10;
		s += f4;
		f1 = f2;
		f2 = f3;
		f3 = f4;
	}
	printf("%d\n",s);
	return 0;
}