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#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <cmath>
using namespace std;
int countSet(vector<int> nums, int K) {
    sort(nums.begin(), nums.end());
    int n = nums.size();
    int left = 0, right = n - 1;
    long long res = 0;
    while (left < right) {
        int sumx = nums[left] + nums[right];
        if (sumx > K) right--;
        else {
            int shift = right - left;
            long long tmp = 1;
            while (shift > 30) {
                tmp <<= 30;
                tmp %= 1000000007;
                shift -= 30;
            }
            tmp <<= shift;
            tmp %= 1000000007;
            res = (res + tmp) % 1000000007;
            left++;
        }
    }
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