Randomly select some different numbers from the natural numbers 1 to 50. To ensure that the sum of the digits of three numbers must be equal, then at least how many numbers should be taken out.
从1至50这些自然数中任意取出一些不同的数，要保证其中一定存在三个数的各位数字之和相等，那么至少要取出多少个数．
<gadget id="calculator">11 * 2</gadget>
<output>22</output>

<gadget id="calculator">22 + 2</gadget>
<output>24</output>

<gadget id="calculator">24 + 1</gadget>
<output>25</output>

<result>25</result>