Rikka with Chess
Time Limit: 2000/1000 MS (Java/Others)
Memory Limit: 65536/65536 K (Java/Others)
Yuta gives Rikka a chess board of size $n \times m$.
As we all know, on a chess board, every cell is either black or white and every two cells that share a side have different colors.
Rikka can choose any rectangle formed by board squares and perform an inversion, every white cell becomes black, and vice versa.
Rikka wants to turn all cells into the same color, please tell Rikka the minimal number of inversions she need to achieve her goal.
The first line contains a number $T(T \leq 10)$ ——The number of the testcases.
Each testcase contains two numbers $n,m(n \leq 10^9, m \leq 10^9)$.
For each testcase, print a single number which represents the answer.
BestCoder Round #73 (div.2)