Recently, Greg got a grid with n rows and m columns. Rows are indexed from 1 to n and columns are indexed from 1 to m. The cell $ ( i , j )$ is the cell of intersection of row i and column j. Each cell has a number written on it. The number written on cell $( i , j )$ is equal to $(i+j)$.
Now, Greg wants to select some cells from the grid, such that for every pair of selected cells ,the numbers on the cells are co-prime. Determine the maximum number of cells that Greg can select.

------ Input ------

Single line containing integers n and m denoting number of rows and number of columns respectively.

------ Output ------

Single line containing the answer.

------ Constraints ------

$$1 ≤ n,m ≤ 10^{6}$$

----- Sample Input 1 ------
3 4

----- Sample Output 1 ------
4

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