★ solved.ac 난이도 : B3 (작성 시점 기준) [문제 본문 링크] 3507번: Automated Telephone Exchange In St Petersburg phone numbers are formatted as “XXX–XX–XX”, where the first three digits represent index of the Automated Telephone Exchange (ATE). Each ATE has exactly 10 000 unique phone numbers. Peter has just bought a new flat and now he wants www.acmicpc.net ★ 문제 번역 St Petersburg에서 전화번호는 "XXX-XX-XX" 형식으로 되어 있으며,..