Recaman's Sequence

Time Limit: 1 Second    Memory Limit: 32768 KB

The Recaman's sequence is defined by a⁰ = 0 ; for m > 0, a^m = a^m-1 - m if the rsulting a^m is positive and not already in the sequence, otherwise a^m = a^m-1 + m.

The first few numbers in the Recaman's Sequence is 0, 1, 3, 6, 2, 7, 13, 20, 12, 21, 11, 22, 10, 23, 9... . Given k, your task is to calculate a^k.

Input

The input consists of several test cases. Each line of the input contains an integer k where 0 <= k <= 500000. The last line contains an integer -1, which should not be processed.

Output

For each k given in the input, print one line containing a^k to the output.

Sample Input

7
10000
-1

Sample Output

20
18658

Submit

Source: Asia 2004, Shanghai (Mainland China), Preliminary