Codeforces Round 473 (Div. 2)
F
Mahmoud and Ehab and yet another xor task
Codeforces
2400
原题
← E→
翻译中…

Ehab has an array $*a*$ of $*n*$ integers. He likes the bitwise-xor operation and he likes to bother Mahmoud so he came up with a problem. He gave Mahmoud $*q*$ queries. In each of them, he gave Mahmoud 2 integers $*l*$ and $*x*$, and asked him to find the number of subsequences of the first $*l*$ elements of the array such that their bitwise-xor sum is $*x*$. Can you help Mahmoud answer the queries?

翻译中…

A subsequence can contain elements that are not neighboring.

翻译中…

Input

翻译中…

The first line contains integers $*n*$ and $*q*$ $(1 ≤ *n*, *q* ≤ 10^{5})$, the number of elements in the array and the number of queries.

翻译中…

The next line contains $*n*$ integers $*a*_{1}$, $*a*_{2}$, $...$, $*a*_{*n*}$ $(0 ≤ *a*_{*i*} < 2^{20})$, the elements of the array.

翻译中…

The next $*q*$ lines, each contains integers $*l*$ and $*x*$ $(1 ≤ *l* ≤ *n*$, $0 ≤ *x* < 2^{20})$, representing the queries.

翻译中…

Output

翻译中…

For each query, output its answer modulo $10^{9} + 7$ in a newline.

翻译中…

Note

翻译中…

The bitwise-xor sum of the empty set is 0 and the bitwise-xor sum of a set containing one element is that element itself.

翻译中…

样例

Input #1
5 5
0 1 2 3 4
4 3
2 0
3 7
5 7
5 8
Output #1
4
2
0
4
0
InputCopy OutputCopy
Input #2
3 2
1 1 1
3 1
2 0
Output #2
4
2
InputCopy OutputCopy
题目信息
题号
959F
时间限制
1 s
内存限制
512 MB
标签
位运算
动态规划
数学
矩阵

题面与样例版权归 Codeforces 及出题人所有;中文翻译由 AI 生成(CI 管线),如有出入请以原文为准。