## Goal

Your program must decode the encoded message from the Chuck Norris encoding project.

It is strongly recommended to have done the Chuck Norris project.

Link -> **https://www.codingame.com/training/easy/chuck-norris**

Here are some reminders about the Chuck Norris encoding method:

- The encoded message is unary, containing only sequences of zeroes separated by spaces.

- These sequences of zeroes always come in pairs.

- The first sequence of a pair can be either 0 or 00, which represent the binary bits 1 and 0 respectively.

- The second sequence of a pair is made of k zeroes, where k is the number of time the previous bit has to be printed in order to decode the message.

For instance, if we want to encode the character **A**, we first start to write down the 7-bit ASCII code for **A** which is 1000001 in binary. (We only use 7 bits because the first bit is always zero so it's ignored).

Then we turn the binary into unary as follows:

**1**000001 -> 0 0 (bit 1, one time)

1**00000**1 -> 00 00000 (bit 0, five times)

100000**1** -> 0 0 (bit 1, one time)

Therefore, the encoded message is **0 0 00 00000 0 0**.

You are asked to do the reverse process, and thus print A when given the message **0 0 00 00000 0 0**.

If the input is invalid, just print **INVALID**.
Input

**Line 1:** The encoded message of N characters.

Output

**Line 1:** The decoded message, or the word **INVALID** when the input is not valid.