vardef numbers = array<int>(13) [
  0, 1, 2, 2, 3, 4, 4, 5, 6, 7, 8, 8, 9
];
vardef tgt = 0;
vardef src = 1;
while src < len(numbers) {
  print "src: ", src, "; tgt: ", tgt;
  if numbers[src] != numbers[tgt] {
    tgt = tgt + 1;
    numbers[tgt] = numbers[src];
  }
  src = src + 1;
}
print "New length: ", tgt;