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Easy One

시간 제한3초메모리 제한512 MB

요약
1과 2로 이루어진 수열에서 네 가지 연산만 써서 2가 a개인 수열을 2가 b개인 수열로 정확히 t번 만에 바꾸는 방법의 수를 센다.
난이도

보통10점 중 7점

유형
조합론, 동적 계획법, 수학
정답자
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문제

You have a sequence of digits 11 and 22. In one step you can:

  1. Insert 11 in a place which is to the right of every other 11 (or anywhere if there are no 11s).
  2. Transform any 22 into 11, if there are no 11s to the right of this 22.
  3. Delete the rightmost 11 (note that this operation is inverse to the operation 1).
  4. Transform the rightmost 11 into 22 (note that this operation is inverse to the operation 2).

For example, you can obtain the following sequences in one step from the sequence 11212122:

  • With operation 1: 112121122, 112121212, 112121221.
  • With operation 2: 11212112, 11212121.
  • With operation 3: 1121222.
  • With operation 4: 11212222.

Your task is to calculate the number of ways to transform a sequence of exactly aa digits 22 to a sequence of exactly bb digits 22, using exactly tt operations.

입력

The only line of the input contains three integers aa, bb, and tt (0≤a,b,t≤1060 \le a, b, t \le 10^6).

출력

Output the number of ways to obtain a sequence of bb digits 22 from a sequence of aa digits 22 in exactly tt steps. As this number can be very large, output it modulo prime number 998,244,353998\\,244\\,353.

힌트

In the first sample you should obtain an empty sequence from an empty sequence in 4 steps. Ways to do this are (ε\varepsilon stands for empty sequence):

ε→1→ε→1→ε\varepsilon \to 1 \to \varepsilon \to 1 \to \varepsilon  ε→1→11→1→ε \varepsilon \to 1 \to 11 \to 1 \to \varepsilon ε→1→2→1→ε \varepsilon \to 1 \to 2 \to 1 \to \varepsilon

예제2

  1. 예제 1

    입력
    0 0 4
    
    예상 출력
    3
    
  2. 예제 2

    입력
    1 4 6
    
    예상 출력
    60