const fs = require("fs");

const file = "inputs/2";
const fileContent = fs.readFileSync(file, "utf-8").trim();

const reports = fileContent.split("\n");

let safeCount = 0;

function isSafe(numbers) {
  const isIncreasing = numbers.every(
    (num, i) => i === 0 || num > numbers[i - 1]
  );

  const isDecreasing = numbers.every(
    (num, i) => i === 0 || num < numbers[i - 1]
  );

  const isValidJumps = numbers.every(
    (num, i) => i === 0 || Math.abs(num - numbers[i - 1]) <= 3
  );

  return (isIncreasing || isDecreasing) && isValidJumps;
}

for (const element of reports) {
  const arr = element.trim().split(" ");
  const numbers = arr.map(Number);

  if (isSafe(numbers)) {
    safeCount += 1;
    continue;
  }

  let isSafeAfterRemoval = false;

  for (let i = 0; i < numbers.length; i++) {
    const newNumbers = numbers.slice(0, i).concat(numbers.slice(i + 1));
    if (isSafe(newNumbers)) {
      isSafeAfterRemoval = true;
      break;
    }
  }

  if (isSafeAfterRemoval) {
    safeCount += 1;
  }
}

console.log(safeCount);