https://www.acmicpc.net/problem/3507 3507λ²: 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 Automated Telephone Exchange [μλ μ ν κ΅ν] μκ° μ νλ©λͺ¨λ¦¬ μ νμ μΆμ λ΅λ§ν μ¬λ..