Claim: Mathematical Grammar School,  a special school for gifted and talented students, won 121 medals in the International Mathematics Olympiad.
Evidence: Mathematical Grammar School (Serbian: Matematička gimnazija Beograd / Математичка гимназија Београд, abbr. "MG" or "MGB"), is a special school for gifted and talented students of mathematics, physics and informatics located in Belgrade, Serbia. 121 International Mathematics Olympiad