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Question: 2015 Fall Midterm - 7

Author: Michiel Smid
In the city of $\ShortLastName$, every person has a last name consisting of two characters, the first one being an uppercase letter and the second one being a lowercase letter. What is the minimum number of people needed so that we can guarantee that at least 4 of them have the same last name?
(a)
$3 \cdot 26^{2}$
(b)
$3 \cdot 26^{2} + 1$
(c)
$4 \cdot 26^{2} + 1$
(d)
$4 \cdot 26^{2}$