What is the answer to puzzle 87 in Professor Layton and the Diabolical Box?

Puzzle No 81: The Old Safe.Location, Mine Vault.

This puzzle is also know as The Old Safe. You may have just finished puzzle number 82, Restarting the Lift. Press the elevator buttons, must have solved puzzle number 80. Examine the bottom left corner of the back wall, the top of the elevator hand rail on the right, and the lamp on the right for hint coins. Check out the safe on the wall. The code 0154 opens the safe. you might want to try puzzle number 82, Restarting the Lift next.

the answer is 0154 or the code 0154 opens the safe

Please see the Related link below for a walkthrough of puzzle 81.