#include<stdio.h>
int v[3];
long long s;
int main()
{
	freopen("koba.in","r",stdin);
	freopen("koba.out","w",stdout);
	int n,i,x1=2,x2=1,x3=0;
	scanf("%d",&n);
	for(i=0; i<3; i++)
	{
		scanf("%d",&v[i]);
		v[i]=v[i]%10;
		if(i<n)
			s+=v[i];
	}
	for(i=4; i<=n; i++)
	{
		v[x3]=(v[x1]+v[x2]*v[x3])%10;
		s+=v[x3];
		if(x1==2)
			x1=0;
		else
			x1++;
		if(x2==2)
			x2=0;
		else
			x2++;
		if(x3==2)
			x3=0;
		else
			x3++;
	}
	printf("%lld\n",s);
	return 0;
}