What are the time complexities of the following code segments?

(a)

for i := 1 to n do 

 for j := 1 to n2 do 

 for k := 1 to n3 do 

 a[i,j,k] := 0 

(b)

function comp(n) 

{ 

 if n < 2 then return 1 

 return comp( n / 2 ) 

}