var n,t1,t2,t3,i,r:longint;
f,g:text;
s:longint;
begin
assign(f,'koba.in');reset(f);
assign(g,'koba.out');rewrite(g);
read(f,n,t1,t2,t3);
s:=(t1 mod 10)+(t2 mod 10)+(t3 mod 10);
for i:=4 to n do begin
r:=(t3 mod 10)+(t2 mod 10)*(t1 mod 10);
s:=s+(r mod 10);
t1:=t2;
t2:=t3;
t3:=r mod 10;
end;
writeln(g,s);
close(f);
close(g);
end.