⟩ I wrote letters to four different people and wrote their addresses on four envelopes. But while inserting each letter into an envelope. I was careless. Either I put three letters in right envelopes, or I put two letters in right envelopes or I put one letter in wrong envelope, what did I do?
you put 2 letters in the right envelope and 2 in the wrong
as it is not possible to put 3 right letters or 1 wrong
letter because if 3 letters are put correctly then the
fourth one has to be in the right envelope
