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Задачи

1821. Bet

Ограничения: время – 1s/2s, память – 64MiB Ввод: input.txt или стандартный ввод Вывод: output.txt или стандартный вывод copy
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Mirko doesn't like Latin homeworks so he made a bet with Slavko. Loser will be writing homeworks for both of them the entire month. Mirko wants to win so he designed this problem they could have something to bet on.

At his desk he found a cube, with numbers 1 to 6 on its faces. Cube is shown on the picture. Additionally, sum of the numbers on opposing faces is equal to 7. That means that 6 is on the opposite face of 1, 5 on the opposite of 2 and 4 on the opposite face of 3.

Mirko has put the cube in the upper left field of the matrix of `R` rows and `C` columns. The cube is initially oriented in a way that upper side is showing number 1, and side to the right number 3.

Mirko now makes te following moves:

He is rolling the cube to the right, until it reaches the last column
Then he rolls it down (to the next row)
Now he rolls the cube to the left, until it reaches first column
Like in step 2, he rolls it down (to the next row)

Mirko is repeating these steps for as long as he can, i.e. as long as he can roll the cube in the next row. When a cube reaches some field, Mirko writes down the number on the top of the cube. In the end he sums all of the numbers he had written.

Mirko made a bet with Slavko that he could calculate that sum without error. Help Slavko verifying Mirko’s solution!

First and only line of input contains two positive integers. `R` and `C` (`1\ ≤\ R,\ C\ ≤\ 100\ 000`), matrix dimensions.

First and only line of input should contain the sum described in the task.

Sample Input #1

3 2

Sample Output #1

Sample Input #2

3 4

Sample Output #2

Sample Input #3

737 296

Sample Output #3

First sample description: numbers Mirko wrote down are:

1 4 
1 5 
3 5

Source: COCI 2011/2012

25/06/2012	Лето 2012 - дорешивание (12D)
12/07/2012	Лето 2012 - 12 (командный) (D)