a.cpp

#include<bits/stdc++.h>
using namespace std;
int main()
{
    int tst;
    cin >> tst;
    while (tst--) {
        int n;
        cin >> n;
        cout<<n<<endl;
        if (n == 1) {cout << "1\n1 1\n"; continue;}
        int m[n + 1] = {0};
        vector<int>v[n / 2];
        v[0].push_back(1);
        int x = 0;
        for (int i = 2; i <= n; i+=2)
        {
            m[i]++;
            v[x++].push_back(i);
        }
        for (int i = 3; i <= n; i+=2)
        {
            x = 0;
            if(!m[i]){
                for (int j = i; j <= n; j+=2*i)
                {
                    if(!m[j]){
                        if((x+1)%i==0){
                            x++;
                        }
                        if(x<n/2)v[x++].push_back(j),m[j]++;
                        else break;
                    }
                }
            }
        }
        cout << n / 2 << "\n";
        for (int i = 0; i < n / 2; i++) {
            cout << v[i].size() << " ";
            for (int j = 0; j < v[i].size(); j++)cout << v[i][j] << " ";
            cout << "\n";
        }
        cout<<endl;
    }
}