BdMO National 2015 Secondary Problem 1.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?