#include  "library.h"

int collatz(const int start)
{ int count = 0;
  int val = start;
  while (val != 1)
                   // another test for is it odd is: if (val & 1)
  { if (val % 2 == 0)
      val = val / 2;
    else
      val = val * 3 + 1;
    count = count + 1;
    cout << count << ": " << val << "\n"; }
  return count; }

void main()
{ while (true)
  { cout << "starting value? ";
    cin >> n;
    const int k = collatz(n);
    cout << "length of sequence starting from " << n << " is " << k << "\n"; } }