#include<stdio.h>
int main()
{
long n,t1,t2,t3,ti,s=0,i;

freopen("koba.in","r",stdin);
freopen("koba.out","w",stdout);

scanf("%ld %ld %ld %ld",&n,&t1,&t2,&t3);
t1=t1%10;
t2=t2%10;
t3=t3%10;
s=(long)t1+t2+t3;
for(i=4;i<=n;i++)
   {
     t1=t1%10;
     t2=t2%10;
     t3=t3%10;
     ti=t3+t2*t1;
     ti=ti%10;
     s=(long)s+ti;
     t1=t2;
     t2=t3;
     t3=ti;
   }
printf("%ld",s);
return 0;
}