5. (8 points) Fill in the blanks with $1-6$, so that the numbers in each row and each column are not repeated. The two cells occupied by the same symbol in the figure have the same number combination, but the order is uncertain. Therefore, the five-digit number formed by the first five numbers from left to right in the last row is

保留源文本的换行和格式，直接输出翻译结果。
46123
【Solution】Solution: According to the problem, we know:
First, the number in the second row and second column can only be 5, and the number in the third row and fourth column can only be 6.
Continuing the reasoning, the solution is as shown in the figure:
Therefore, the answer is: 46123.