Cryptogram Cracking Club

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시간 제한2초메모리 제한2048 MB

요약
런 렝스 인코딩으로 주어진 패턴을 무한히 반복한 문자열에서 c번째 문자를 찾는다.
난이도

보통10점 중 4점

유형
문자열, 구현, 수학, 이분 탐색
정답자
아직 제출이 없습니다

문제

Cyrene, the captain of the Cryptogram Cracking Club (CCC), came across a concerningly long cipher. Conveniently, this cipher is composed of lower-case characters (a-z). Comfortingly, the cipher is composed of a pattern that repeats infinitely.

Cyrene wishes to locate the cc-th character of the cipher. To make your job easier, the CCC members have extracted the repeated pattern and compressed it using the Run-Length Encoding (RLE) algorithm, which replaces consecutive repeated characters with a single occurrence of the character followed by a count of how many times it was repeated. For example, for the pattern aaaabccdddd, the RLE algorithm outputs a4b1c2d4.

You are given the output of the RLE algorithm for a certain pattern. Can you determine the cc-th character of the long cipher that is formed by repeating this pattern infinitely?

입력

The first line of input will consist of a string SS, representing a pattern produced by the RLE algorithm. The length of SS will be at least 22 and at most 2⋅1052 \cdot 10^5. Additionally, all numbers appearing in SS are between 11 and 101210^{12}.

The next line of input contains a single integer cc (0≤c≤1012),representingtheindexofthecharacteryouwishtolocate,startingfromindex0 ≤ c ≤ 10^{12}), representing the index of the character you wish to locate, starting from index 0$.

출력

Output the cc-th character of the long cipher.

예제2

  1. 예제 1

    입력
    r2d2
    8
    
    예상 출력
    r
    
  2. 예제 2

    입력
    a4b1c2d10
    100
    
    예상 출력
    d