Ugly Number 的定義為：該數之質因數必須為 2、3 或 5。

1, 2, 3, 4, 5, 6, 8, 9, 10, 12, 15


No input

## Output

The 1500'th ugly number is <number>.


## Attention

Your program must be smart enough to solve this problem in 30 seconds. If your program is not so efficient, it may take much time to run. Please be patient.