<image>(2011 Autumn • Jiaxing School-Level Midterm) As shown in the figure, the graph of the function f(x) is a piecewise linear segment ABC, where the coordinates of points A, B, and C are (0, 4), (2, 0), and (6, 4) respectively. If the range of f(x) is [0, 4] and the domain is [m, n], then the minimum value of |m - n| is ____.