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Annchelijk
A company produces many types of watches. The type of each watch is indicated with a string of five characters. The two first characters are based on uppercase alphabets, except I, O, and Q. The next three characters are three digit of numbers ranging from 000 to 300. Determine the minimum number of watches to ensure that at least three of them have the same type.
if repitition is allowed then for the first two place we have 23*23 choices and for the next three character we have 4*10*10 choices hence total no is 211600 but here the watches are all of different type