#include<stdio.h>

#define INPUT "koba.in"
#define OUTPUT "koba.out"

void Rezolvare();
long long unsigned n,a,b,c,aux,suma;

int main()
{
	freopen(INPUT,"r",stdin);
	freopen(OUTPUT,"w",stdout);
	Rezolvare();
	return 0;
}
void Rezolvare()
{
	int i;
	scanf("%llu%llu%llu%llu",&n,&a,&b,&c);
	a=a%10;
	b=b%10;
	c=c%10;
	suma=a+b+c;
	for(i=4; i<=n; ++i)
	{
	     aux=(c+b*a)%10;
	     a=b;
	     b=c;
	     c=aux;
	     suma+=aux;
	}
	printf("%llu",suma);
}