#P15591. [ICPC 2020 Jakarta R] Moon and Sun

[ICPC 2020 Jakarta R] Moon and Sun

Problem Description

Let SS be a non-empty sequence of integers and KK be a positive integer. The functions moon()moon() and sun()sun() are defined as follows.

$$moon(S_{1..|S|}) = \begin{cases} S & \text{if } |S| = 1 \\ [S_2 - S_1, S_3 - S_2, \dots, S_{|S|} - S_{|S|-1}] & \text{if } |S| > 1 \end{cases}$$$$sun(S_{1..|S|}, K) = \begin{cases} S & \text{if } K = 1 \\ sun(moon(S_{1..|S|}), K - 1) & \text{if } K > 1 \end{cases}$$

For example,

  • moon([2,7])=[5]moon([2, 7]) = [5].
  • moon([4,1,0,7,2])=[−3,−1,7,−5]moon([4, 1, 0, 7, 2]) = [-3, -1, 7, -5].
  • $sun([4, 1, 0, 7, 2], 5) = sun([-3, -1, 7, -5], 4) = sun([2, 8, -12], 3) = sun([6, -20], 2) = sun([-26], 1) = [-26]$.

Observe that sun(S1..∣S∣,∣S∣)sun(S_{1..|S|}, |S|) is always a sequence with exactly one element.

You are given a sequence of NN integers A1..NA_{1..N}. An index i=[1..N]i = [1..N] is hot if and only if there exists a sequence A1..N′A'_{1..N} satisfying the following conditions:

  • Ai′≠AiA'_i \ne A_i and Ai′A'_i is an integer between −100 000-100\,000 and 100 000100\,000, inclusive;
  • Aj′=AjA'_j = A_j for all j≠ij \ne i;
  • The only element in sun(A1..N′,N)sun(A'_{1..N}, N) is a multiple of 235 813235\,813.

Your task in this problem is to count the number of hot indices in a given A1..NA_{1..N}.

For example, there are 33 hot indices in A1..5=[4,1,0,7,2]A_{1..5} = [4, 1, 0, 7, 2], which are {1,3,5}\{1, 3, 5\}.

  • i=1i = 1, A1′=30A'_1 = 30 → A1..5′=[30,1,0,7,2]A'_{1..5} = [30, 1, 0, 7, 2] → sun([30,1,0,7,2],5)=[0]sun([30, 1, 0, 7, 2], 5) = [0]
  • i=3i = 3, A1′=−78 600A'_1 = -78\,600 → A1..5′=[4,1,−78 600,7,2]A'_{1..5} = [4, 1, -78\,600, 7, 2] → sun([4,1,−78 600,7,2],5)=[−471 626]sun([4, 1, -78\,600, 7, 2], 5) = [-471\,626]
  • i=5i = 5, A1′=28A'_1 = 28 → A1..5′=[4,1,0,7,28]A'_{1..5} = [4, 1, 0, 7, 28] → sun([4,1,0,7,28],5)=[0]sun([4, 1, 0, 7, 28], 5) = [0]

Note that both 00 and −471 626-471\,626 are multiples of 235 813235\,813. On the other hand, the index i=2i = 2 is not hot as there does not exist an integer A2′≠A2A'_2 \ne A_2 between −100 000-100\,000 and 100 000100\,000, inclusive, such that the only element in sun(A1..5′,5)sun(A'_{1..5}, 5) is a multiple of 235 813235\,813. The index i=4i = 4 is also not hot for a similar reason.

Input Format

Input begins with a line containing an integer: NN (1≤N≤100 0001 \leq N \leq 100\,000) representing the number of integers in AA. The next line contains NN integers: AiA_i (−100 000≤Ai≤100 000-100\,000 \leq A_i \leq 100\,000) representing the sequence of integers.

Output Format

Output in a line an integer representing the number of hot indices in the given A1..NA_{1..N}.

5
4 1 0 7 2
3
4
10 20 30 -40
4
2
100 100
0

Hint

Explanation for the sample input/output #1

This is the example from the problem description.

Explanation for the sample input/output #2

  • i=1i = 1, A1′=−70A'_1 = -70 → A1..4′=[−70,20,30,−40]A'_{1..4} = [-70, 20, 30, -40] → sun([−70,20,30,−40],4)=[0]sun([-70, 20, 30, -40], 4) = [0]
  • i=2i = 2, A2′=78 651A'_2 = 78\,651 → A1..4′=[10,78 651,30,−40]A'_{1..4} = [10, 78\,651, 30, -40] → sun([10,78 651,30,−40],4)=[235 813]sun([10, 78\,651, 30, -40], 4) = [235\,813]
  • i=3i = 3, A3′=−78 601A'_3 = -78\,601 → A1..4′=[10,20,−78 601,−40]A'_{1..4} = [10, 20, -78\,601, -40] → sun([10,20,−78 601,−40],4)=[235 813]sun([10, 20, -78\,601, -40], 4) = [235\,813]
  • i=4i = 4, A4′=40A'_4 = 40 → A1..4′=[10,20,30,40]A'_{1..4} = [10, 20, 30, 40] → sun([10,20,30,40],4)=[0]sun([10, 20, 30, 40], 4) = [0]