import java . io . BufferedReader ; import java . io . InputStreamReader ; public class Quiz { public static void main ( String [ ] args ) throws Exception { int a ; BufferedReader in = new BufferedReader ( new InputStreamReader ( System . in ) ) ; int i = 0 ; System . out . println ( "=== 구구단 출력 프로그램 ==="); System . out . print ( " 1 ~ 20 단 중 선택 : "); a = Integer . parseInt ( in . readLine ( ) ) ; while ( i < 20 ) { i ++; System . out . println ( a + "*"+ i +"="+ a * i ) ; } }}