$3.$ How many lines does the below program print? Write your solution in big$-$O form.Assume $f_1,f_2,g_1,g_2$ are non$-$negative functions. Suppose that $f_1(n)=$

$O(g_1(n))$ and $f_2(n)=O(g_2(n)).$ Prove that $f_1(n)f_2(n)=O(g_1(n)g_2(n)).$

$1$: function Print$($int N$)$

$2$: if N $>1$:

$3$: print $$printing$$

$4$: Print$($N$/2)$

$5$: Print$($N$/2)$

$6$: Print$($N$/2)$

$7$: end function