program koba;
{$APPTYPE CONSOLE}  
uses  
  SysUtils;   
  
var i,j,n,m:integer;   
    rez,t1,t2,t3,t4,a1,a2,a3,a4:Int64;   
    fin,fout:text;

{*----------------------------------*}
begin
        assign(fin,'koba.in'); reset(fin);
        assign(fout,'koba.out'); rewrite(fout);

        read(fin,n,t1,t2,t3);  rez:=0;
        T1:=T1 mod 10; T2:=T2 mod 10; T3:=T3 mod 10;
         i:=0;
        while i< n do
        begin
                inc(i);
                t4:=t3+t2*t1;
                t4:=t4 mod 10;   
  
                a1:=t2;   
                a2:=t3;   
                a3:=t4;   
                t3:=a3;   
                t2:=a2;   
                t1:=a1;   
  
                rez:=rez+t4;   
  
        end;
  
       writeln(fout,rez);;
  
        close(fin);   
        close(fout);   
end.