const fs = require(\"node:fs\");

const input = fs
  .readFileSync(\"./day4-input.txt\", \"utf8\")
  .split(\"\\n\")
  .map((line) => line.split(\"\"));

let count = 0;

for (let y = 0; y < input.length; y++) \{
  for (let x = 0; x < input[y].length; x++) \{
    if (input[y]?.[x] !== \"A\") \{
      continue;
    \}

    let s1, s2;

    s1 = input[y - 1]?.[x - 1];
    s2 = input[y + 1]?.[x + 1];

    if (![\"MS\", \"SM\"].includes(\`\$\{s1\}\$\{s2\}\`)) \{
      continue;
    \}

    s1 = input[y + 1]?.[x - 1];
    s2 = input[y - 1]?.[x + 1];

    if (![\"MS\", \"SM\"].includes(\`\$\{s1\}\$\{s2\}\`)) \{
      continue;
    \}

    count++;
  \}
\}

console.log(count);