Daily programmer #158, in Brainfuck

158.bf

first digit
,------------------------------------------------
[>++++++++++<-]

second digit
,------------------------------------------------
>>

third digit
,------------------------------------------------
[>++++++++++<-]

fourth digit
,------------------------------------------------

make the first number
<<
[>+<-]

make the second number
>>
[>+<-]

add the two numbers into cell 0
<
[<+>>+<-]
>>
[<<<+>+>>-]

make four copies of cell 0
<<<
[>>>+>+>+>+<<<<<<-]

square this number
>>>>>-
[
  <[<+>-]
  >-
  >[<<+>>>+<-]
  >[<+>-]
  <<
]

make the expected number
<<<
[-<<
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>>]
<[-<+>]

subtract the actual from the expected
<[->>>-<<<]

is the expected nonzero?
>>>
[

  print "n"
  <++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
  .
  

  print "o"
  +
  .

  make this print cell negative 1
  [-]-

  make it 0
  >[-]

]

it was zero!
<+[

  print "yes"
  ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++.
  --------------------.
  ++++++++++++++.

  [-]

]