#include <bits/stdc++.h>

using i64 = long long;
using u64 = unsigned long long;
using u32 = unsigned;

void solve() {
    int n, x;
    std::cin >> n >> x;
    
    std::vector<int> p(n);
    std::iota(p.begin(), p.end(), 1);
    
    int ans = n;
    for (int i = n - 2; i >= 0; i--) {
        if (p[i] + p[i + 1] > x) {
            ans--;
            std::swap(p[i], p[x - i - 3]);
        }
    }
    
    std::cout << ans << "\n";
    for (int i = 0; i < n; i++) {
        std::cout << p[i] << " \n"[i == n - 1];
    }
}

int main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
    
    int t = 1;
    std::cin >> t;
    
    while (t--) {
        solve();
    }
    
    return 0;
}