I graduated as a Valedictorian at  my high school
Nice, you must have been the student with the highest ranking GPA among your graduating class.
Of course yes. I am the best student in the school. I put a lot of hard work to my studies 
The term Valedictorian derives from the Latin "vale dicere" which means "to say farewell".
Hmmm. I love the program in our school. I have been looking forward to mine two years earlier
Nice!  In Australia the title Valedictorian is sometimes awarded to a member of the class that contributed a lot, and not necessarily the best academic.
I see. But what kind of contribution could that be?
valedictorian's traditional role as the final speaker at the graduation ceremony before the students receive their diplomas. The valedictory address generally is considered a final farewell to classmates, before they disperse to pursue their individual paths after graduating.
In Australia, New Zealand, South Africa, Ireland, India and the United Kingdom, the title valedictorian is not used frequently. In Australia, the title is sometimes awarded to a member of a graduating university class on the basis of contribution to the school rather than academic success. The highest-
Valedictorian
Valedictorian is an academic title of success used in the United States, Canada, Philippines, and Armenia (and elsewhere in limited number of schools) for the student who delivers the closing or farewell statement at a graduation ceremony (called a valediction). The chosen valedictorian is traditionally the student with the highest ranking (highest Grade Point Average, or GPA) among their graduating class. The term is an Anglicised derivation of the Latin "vale dicere" ("to say farewell"), historically rooted in the