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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?

Problem Statement