'use strict';
const crypto = require('crypto');

function joined(key, i, j) {
  i = BigInt(i); j = BigInt(j);
  if (i > j) [i, j] = [j, i];
  const msg = Buffer.alloc(48);
  key.copy(msg, 0);
  msg.writeBigUInt64BE(i, 32);
  msg.writeBigUInt64BE(j, 40);
  return (crypto.createHash('sha256').update(msg).digest()[0] >> 7) === 1;
}

if (require.main === module) {
  const [key, i, j] = process.argv.slice(2);
  console.log(joined(Buffer.from(key, 'hex'), i, j) ? 1 : 0);
}
module.exports = { joined };