Program koba;
VAR
f,g:text;
v:array [1..1000] of word;
n,s,i:longint;
begin
  assign(f,'koba.in');reset(f);
  assign(g,'koba.out');rewrite(g);
  readln(f,n,v[1],v[2],v[3]);
  s:=s+(v[1] mod 10);
  s:=s+(v[2] mod 10);
  s:=s+(v[3] mod 10);
  for i:=4 to n do
   begin
     v[i]:=(v[i-1] mod 10)+(v[i-2] mod 10)*(v[i-3]mod 10);
     s:=s+(v[i] mod 10);
   end;
  writeln(g,s);
  close(f);close(g);
end.