// Javascript
function sockMerchant(n, ar) {
    let pairCount = 0;
    let i = 0;
    ar.sort((a,b) => a - b);
    while(i < n - 1){
        if(ar[i] == ar[i+1]){
            pairCount++;
            i+=2;
        }
        else {
            i++;
        }
    }
    return pairCount;
}