text: #include <iostream>
  #include <fstream>
  #include <random>
  #include <ctime>
  using namespace std;
  typedef uniform_int_distribution<> rnd;
  typedef uniform_real_distribution<> rndf;
  mt19937 egn(time(nullptr));
  const int CASES = 10;
  int main(int argc, char const* argv[])
  {
      for(int t=1;t<=CASES;t++)
      {
          ofstream fout(to_string(t)+".in");
          // ==============================
          int _t=1e5;
          fout<<_t<<endl;
          for(int i=0;i<_t;i++)
          {
              int n=rnd(1,1e9)(egn), m=rnd(1,n)(egn);
              fout<<n<<' '<<m<<endl;
          }
          // ==============================
          fout.close();
      }
      return 0;
  }