Pills

Grandpa Jongsu takes half a pill every day. His granddaughter Seonyoung gave him a bottle containing N pills.

On the first day, he takes one pill out of the bottle. Since it is a whole pill, he splits it in half, eats one half, and puts the other half back into the bottle.

From the second day on, he takes one item out of the bottle. What he draws may be a whole pill or a half that was split earlier. If it is a half, he simply eats it. If it is a whole pill, he splits it in half, eats one half, and puts the other half back.

On a day he draws a whole pill, he texts his granddaughter W; on a day he draws a half, he texts H. She writes the letters down in order. Emptying the bottle takes exactly $2N$ days, so a string of length $2N$ is produced.

Depending on the order in which the items are drawn, different strings can result. How many distinct strings are possible?

The input consists of at most 1000 test cases. Each test case is a single line containing the number of pills $N$ ($N \le 30$).

The last line of the input contains a single 0, which is not processed.

For each test case, print the number of distinct strings that can be produced, one per line.