bee 1379 - Mean Median Problem

The mean of three integers A, B and C is (A + B + C)/3. The median of three integers is the one that would be in the middle if they are sorted in non-decreasing order. Given two integers A and B, return the minimum possible integer C such that the mean and the median of A, B and C are equal.

Input

Each test case is given in a single line that contains two integers A and B (1 ≤ A ≤ B ≤ 10⁹). The last test case is followed by a line containing two zeros.

Output

For each test case output one line containing the minimum possible integer C such that the mean and the median of A, B and C are equal.

Sample Input	Sample Output
1 2 6 10 1 1000000000 0 0	0 2 -999999998