#include<stdio.h>
long n,s,i;
long t1,t2,t3,aux;
int main ()
{
freopen("koba.in","r",stdin);
freopen("koba.out","w",stdout);
scanf("%ld%d%d%d",&n,&t1,&t2,&t3);
if(n<=3)
  {
  if(n==1)
    s+=t1%10;
  if(n==2)
    s+=t1%10+t2%10;
  if(n==3)
    s+=t1%10+t2%10+t3%10;
  } //if n<3
else
  {
  t1=t1%10;
  t2=t2%10;
  t3=t3%10;
  s+=t1+t2+t3;
  for(i=4;i<=n;i++)
    {
    s+=(t1+t2*t3)%10;
    aux=(t1+t2*t3)%10;
    t1=t2;
    t2=t3;
    t3=aux;
    } //for
  }//else

printf("%ld",s);
return 0;
}//main