25. The "great circle" on a globe is a circle that divides the globe into two equal hemispheres, and the two hemispheres divided by the "great circle" are respectively called the "Qian" hemisphere and the "Kun" hemisphere. Points on the "great circle" belong to both the "Qian" hemisphere and the "Kun" hemisphere. Familiar lines on the globe, such as meridians and the equator, are all "great circles". If any 2 points are taken on the globe, there exists 1 "great circle" passing through these two points. Therefore, the minimum number of points that need to be taken on the globe to ensure that at least 4 of these points fall in the same hemisphere is $\qquad$.
$5$