시간 제한메모리 제한제출정답맞힌 사람정답 비율
1 초 128 MB45912910733.333%

문제

상근이는 희원이와 놀기 위해 집에서 게임을 준비해 왔다. 한 종이에 한 글자씩 쓰여 있고, 이러한 종이 N개가 한 줄로 놓여져 있다. 두 사람 각각은 이 종이를 모아서 단어를 만들려고 한다. 각 사람은 턴을 번갈아가면서 종이 한 장을 가져가고 자기 단어의 뒤쪽에 붙인다. 상근이가 게임을 먼저 하고, 더 이상 가져갈 종이가 없으면 게임을 종료한다.

두 단어 A와 B가 있을때, A가 B보다 사전순으로 앞선다면, A는 B보다 아름답다. 두 사람이 각자 만든 단어 중에서 더 아름다운 단어를 만든 사람이 게임을 이긴다. 만약 두 사람이 같은 단어를 만들었다면 둘 다 진다.

상근이는 이 게임을 엄청나게 잘하지만, 희원이는 아직 규칙도 헷갈리는 상황이다. 따라서, 상근이는 희원이를 위해 조금 다르게 게임을 하려고 한다. 상근이는 항상 가장 오른쪽에 있는 종이를 집어간다. 희원이가 이 사실을 알고 있을 때, 희원이가 상근이를 이길 수 있는지 구하고, 만들 수 있는 가장 아름다운 단어를 구하는 프로그램을 작성하시오.

입력

첫째 줄에 짝수 N이 주어진다. (2 ≤ N ≤ 100 000)

둘째 줄에 종이에 적혀 있는 글자가 순서대로 주어진다. 글자는 모두 알파벳 소문자이다.

출력

만약, 희원이가 이길 수 있다면 첫째 줄에 "DA"를, 없다면 "NE"를 출력한다. 둘째 줄에는 희원이가 만들 수 있는 가장 아름다운 단어를 출력한다.

예제 입력 1

2
ne

예제 출력 1

NE
n

예제 입력 2

4
kava

예제 출력 2

DA
ak

예제 입력 3

8
cokolada

예제 출력 3

DA
acko
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

출처

Contest > Croatian Open Competition in Informatics > COCI 2010/2011 > Contest #2 3번