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3. If any$ 2\times2$ squares are removed from a $3\times 3$ squares, then we get a graph which is called an "angle shape" .(One kind of angle shape is shown in the first figure.)Some non-overlapping angle shapes are placed in a $10\times 10$ square table (another figure), the biundaries of the angle shapes coincide with the boundaries or dividing lines of thwe table,Find the maximum integer $k$ , so that whatever way you place $k$ angle shapes in the table, you can always put one more angle shape inside the table.