시간 제한메모리 제한제출정답맞힌 사람정답 비율
2 초 256 MB198594330.935%

## 문제

홀짝 수열은 1,2,4,5,7,9,10,12,14,16,17로 시작하는 증가하는 자연수 수열이다. 홀짝 수열은 1개의 홀수, 2개의 짝수, 3개의 홀수 이런식으로 이어진다. 이 수열의 N번째 원소를 출력한다.

## 입력

첫째 줄에 N(1 ≤ N ≤ 10100)이 주어진다.

## 출력

첫째 줄에 홀짝 수열의 N번째 원소를 출력한다.

## 예제 입력 1

1


## 예제 출력 1

1


## 예제 입력 2

4


## 예제 출력 2

5

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