atcoder#ARC156D. [ARC156D] Xor Sum 5

[ARC156D] Xor Sum 5

Score : 700700 points

Problem Statement

You are given a sequence of NN non-negative integers A=(A1,A2,,AN)A=(A_1,A_2,\dots,A_N) and a positive integer KK.

Find the bitwise XOR\mathrm{XOR} of i=1KAXi\displaystyle \sum_{i=1}^{K} A_{X_i} over all NKN^K sequences of KK positive integer sequences X=(X1,X2,,XK)X=(X_1,X_2,\dots,X_K) such that 1XiN (1iK)1 \leq X_i \leq N\ (1\leq i \leq K).

What is bitwise $\mathrm{XOR}$?

The bitwise $\mathrm{XOR}$ of non-negative integers $A$ and $B$, $A \oplus B$, is defined as follows:

  • When $A \oplus B$ is written in base two, the digit in the $2^k$'s place ($k \geq 0$) is $1$ if exactly one of the digits in that place of $A$ and $B$ is $1$, and $0$ otherwise.
For example, we have 3 \oplus 5 = 6 (in base two: 011 \oplus 101 = 110).
Generally, the bitwise \mathrm{XOR} of k non-negative integers p_1, p_2, p_3, \dots, p_k is defined as (\dots ((p_1 \oplus p_2) \oplus p_3) \oplus \dots \oplus p_k). We can prove that this value does not depend on the order of p_1, p_2, p_3, \dots, p_k.

Constraints

  • 1N10001 \leq N \leq 1000
  • 1K10121 \leq K \leq 10^{12}
  • 0Ai10000 \leq A_i \leq 1000
  • All values in the input are integers.

Input

The input is given from Standard Input in the following format:

NN KK

A1A_1 A2A_2 \dots ANA_N

Output

Print the answer.

2 2
10 30
40

There are four sequences to consider: (X1,X2)=(1,1),(1,2),(2,1),(2,2)(X_1,X_2)=(1,1),(1,2),(2,1),(2,2), for which AX1+AX2A_{X_1}+A_{X_2} is 20,40,40,6020,40,40,60, respectively. Thus, the answer is 20404060=4020 \oplus 40 \oplus 40 \oplus 60=40.

4 10
0 0 0 0
0
11 998244353
314 159 265 358 979 323 846 264 338 327 950
236500026047