#include<fstream.h>
ifstream f("koba.in");
ofstream g("koba.out");
 
int n,t1,t2,t3,s;

long gener(long a,long b, long c)
{
return (c+b*a);
}
int main()
{
f>>n>>t1>>t2>>t3;
s=t1%10+t2%10+t3%10;
for(i=1;i<=n-3;i++)
    {p=gener(t1,t2,t3);
     s+=p%10;
     t1=t2;t2=t3;t3=p;	
    }  
return 0; 
}