var n,i:longint;
        f:text;
procedure back(x,y:longint);
begin
        inc(i);
        if x+y<=n then
        begin
             back(x,x+y);
             back(x+y,y);
        end;
end;
begin
        assign(f,'fractii.in');
        reset(f);
                read(f,n);
        close(f);
        back(1,1);
        assign(f,'fractii.out');
        rewrite(f);
                write(f,i);
        close(f);
end.