{ http://infoarena.ro/problema/cifra }
var f,g:text;
    n,s:int64;
    i:longint;
function putere(n,p:int64):int64;
begin
        if p=0 then putere:=1
               else if odd(p) then putere:=n*putere(sqr(n),(p-1)div 2)
                              else putere:=putere(sqr(n),p div 2);
end;
function uc(n:int64):int64;
begin
        uc:=n mod 10;
end;
{function sumauc(n:int64):int64;
var s,i:int64;
begin
    s:=0;
    for i:=1 to n do
        s:=s+uc(putere(i,i));
    sumauc:=s mod 10;
end;}
begin
        assign(f,'cifra.in'); reset(f);
        assign(g,'cifra.out'); rewrite(g);
        read(f,n);
        s:=0;
        for i:=1 to n do
                s:=s+uc(putere(i,i));
        write(g,s mod 10);
        close(f); close(g);
end.