BdMO National Secondary 2015#1

[samiul_samin]

A crime is committed during the hartal.There are four witnesses.The witnesses are logicians and make the following statement:
●Witness One said exactly one of the four witnesses is a liar.
●Witness Two said exactly two of the four witnesses is a liar.
●Witness Three said exactly three of the four witnesses is a liar.
●Witness Four said exactly four of the four witnesses is a liar.
Assume that each of the statements is either true or false.How many of the winesses are liars?

[samiul_samin]

According the question only third witness is true.So,there are three liars.Actually it is the most paradoxical BdMO National question till now.