The following problem consists of a set of six figures, the first of which is unnumbered and marks the beginning of the series which is continued in the successive figures numbered from (1) to (5). However, the series will be established only if the positions of two of the numbered figures are interchanged. The number of the earlier of the two figures is the answer. If no two figures need to be interchanged, then the answer is (5). Fill in the box with appropriate answer.