4437：swap

There's a matrix of n rows and m columns whose elements are either 0 or 1.
If an element is 0, it is located at the i-th row and j-th column, there is at least one 1 is located at the i-th row and k-th (k < j) column, and at least one 1 is located at the i-th row and r-th(r > j) column, this element is called Cup.
You can swap any two rows and any two columns of the matrix. You can do this infinite times, to minimize the number of Cups.

Multiple test cases (no more than 50), ended with EOF.
The 1st line of each test case contains two integers n and m (3 ≤ n ≤ 10, 3 ≤ m ≤ 25), the number of rows and the number of columns of the matrix.
Then following n lines, each line has m space-separated 0 or 1, indicating the original configuration of the matrix.

For each test case output a number in one line, indicating the number of minimum Cups can be obtained after the swapping operations.