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