Complete MaxExp

Here is the complete subroutine:

## maxExp -- compute the maximum of three expressions
##
## Input:
## $a0 -- a signed integer, x
## $a1 -- a signed integer, y
##           
## Returns: 
## $v0 -- the maximum of x*x,  x*y, or 5*y
##
## Registers:
## $s0 --  x*x
## $s1 --  x*y
## $s2 --  5*y

         .text
         .globl maxExp

maxExp:
         # prolog
         sub     $sp,$sp,4        # push the return address
         sw      $ra,($sp)
         sub     $sp,$sp,4        # push $s0
         sw      $s0,($sp)
         sub     $sp,$sp,4        # push $s1
         sw      $s1,($sp)
         sub     $sp,$sp,4        # push $s2
         sw      $s2,($sp)

         # body
         mul     $s0,$a0,$a0      # x*x
         mul     $s1,$a0,$a1      # x*y
         li      $t0,5
         mul     $s2,$t0,$a1      # 5*y
         
         move    $a0,$s0          # compute max of x*x
         move    $a1,$s1          # and x*y
         jal     maxInt           # current max in $v0
         nop

         move    $a0,$v0          # compute max of
         move    $a1,$s2          # current max, and 5*y 
         jal     maxInt           # total max will be in $v0
         nop
         
         # epilog
         lw      $s2,($sp)        # pop $s2 
         add     $sp,$sp,4                                    
         lw      $s1,($sp)        # pop $s1 
         add     $sp,$sp,4                                    
         lw      $s0,($sp)        # pop $s0 
         add     $sp,$sp,4                                    
         lw      $ra,($sp)        # pop return address
         add     $sp,$sp,4         
         jr      $ra              # return to caller 
         nop