CF959F.Mahmoud and Ehab and yet another xor task

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题目描述

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

A subsequence can contain elements that are not neighboring.

输入格式

The first line contains integers nn and qq (1<=n,q<=105)(1<=n,q<=10^{5}) , the number of elements in the array and the number of queries.

The next line contains nn integers a1a_{1} , a2a_{2} , ...... , ana_{n} (0<=ai<220)(0<=a_{i}<2^{20}) , the elements of the array.

The next qq lines, each contains integers ll and xx (1<=l<=n(1<=l<=n , 0<=x<220)0<=x<2^{20}) , representing the queries.

输出格式

For each query, output its answer modulo 109+710^{9}+7 in a newline.

输入输出样例

  • 输入#1

    5 5
    0 1 2 3 4
    4 3
    2 0
    3 7
    5 7
    5 8
    

    输出#1

    4
    2
    0
    4
    0
    
  • 输入#2

    3 2
    1 1 1
    3 1
    2 0
    

    输出#2

    4
    2
    

说明/提示

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.

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