There are five men, let's say Tarun Harish Lavesh, Manoj, and Manish. All of them have a dot mark in their forehead. They can't see the dot on their own forehead, but can see the ones on others. The owner of WHITE dot is an honest person and will never lie, while the owner of BLACK dot always tell the lie.
This is the statement from Tarun Harish Lavesh, and Manish:
Tarun: 'I see 3 whites and 1 black'
Harish: 'I see 4 black'
Lavesh: 'I see 3 black and 1 white'
Manish: 'I see 4 white'
What color is the dot on each Tarun Harish Lavesh, Manoj, Manish forehead?
Tarun Harish Lavesh, and Mansih stated a contradiction statement, so only one of them can said the truth.
We don't know yet where Manoj stands, it's still possible that he has black or white color.
Thus, the maximum possibility of white dots are 2, that is Manoj and 1 of Tarun Harish Lavesh, and Manish.
Tarun and Manish obviously told the lie, as they said there are 3 and 4 person has white dot, which leave us Harish and Lavesh .
Assuming Harish is white, then he must be telling the truth that he saw 4 black dots, which makes Lavesh a liar. This is an impossible situation, since Lavesh saw 3 black and 1 white (Lavesh has to be a liar, so there must be more than 1 white, meaning it's impossible Harish saw 4 blacks).
The only possibility is Lavesh told the truth.
So, Tarun Harish Manish have black dots, while Lavesh and Manoj have white dots.