function part1(data) {
  let sum = 0;

  let previous = data[data.length - 1];
  for (let i = 0; i < data.length; i++) {
    if (previous == data[i]) {
      sum = sum + parseInt(data[i]);
    }
    previous = data[i];
  }

  return sum;
}

function part2(data) {
  const halfWay = parseInt(data.length / 2);
  let sum = 0;
  let prevIndex = halfWay;

  let previous = data[prevIndex];
  for (let i = 0; i < data.length; i++) {
    if (previous == data[i]) {
      sum = sum + parseInt(data[i]);
    }
    
    if (prevIndex < data.length - 1) {
      prevIndex += 1;
    }
    else {
      prevIndex = 0;
    }
    previous = data[prevIndex];
  }

  return sum;
}