/**
 * Returns number of cells needed for given size of the widget.
 *
 * @param size Widget size in dp.
 * @return Size in number of cells.
 */
private static int getCellsForSize(int size) {
    int n = 2;
    while (70 * n - 30 < size) {
        ++n;
    }
    return n - 1;
}