How to solve three wise men puzzle

each of them have a spot on their forehead, could be blue or white, but at least one is white.

then if other two have blue sports, u know u r white.

and in fact all people have a white spot.

1) the first one can not tell,
then the third one knows: he could be blue or white.

2) the second one:
then the third one still only knows, he could be blue or white,

The 3 wise man can each see 2 white spots so to start with they do not know whether they are blue or white.

However, they then think a while . The fact that none of them immediately declared themselves white can only mean that nobody can see 2 blues.

As they are wise they all know that there can therefore be a maximum of one blue. Therefore if there was a blue the two people seeing it would declare themselves white.

They leave it a while and as nobody declares themselves white they all then conclude that there can not be a blue and they simultaneously declare themselves all white.

the third man reasons that if his spot were black, the second would see a black and a white and would reason that if his spot were black, the third would have seen two black spots and reasoned that his spot was white since there is at least one white.
Since the second one has also shown ignorance, it meant that my spot is white.