function mining(arr) {
  let totalBC = 0;
  let dayBC = 0;
  let left = 0;
  let days = 0;
  let money = 0;
  let totalMoney = 0;
  for (let i = 0; i < arr.length; i++) {
    days++;
    if (days === 3) {
      arr[i] = arr[i] - (arr[i] * 0.3);
    }
    money = arr[i] * 67.51;
    totalMoney += money;
    while (totalMoney >= 11949.16) {
      totalMoney -= 11949.16;
      totalBC++;
      if (totalBC === 1) {
        dayBC = days;
      }
    }
  }
  console.log(`Bought bitcoins: ${totalBC}`);
  if (dayBC > 0) {
  console.log(`Day of the first purchased bitcoin: ${dayBC}`);
  }
  console.log(`Left money: ${totalMoney.toFixed(2)} lv.`);
};