function sockMerchant(n, ar) {
    const pairsOfColors = ar.reduce((obj, num) => {
        obj[num] = (obj[num] || 0) + 1;
        return obj;
    }, {});
    let pairs = [];
    for (let key in pairsOfColors) {
        if (!(pairsOfColors[key] <= 1) && pairsOfColors[key] % 2 === 0) {
            pairs.push(pairsOfColors[key] / 2);
        } else if (!(pairsOfColors[key] <= 1) && pairsOfColors[key] % 2 === 1) {
            pairs.push((pairsOfColors[key] - 1) / 2);
        } else {
            pairs.push(0);
        }
    }
  return pairs.reduce((acc, num) => (acc + num), 0);
}