def count_elements(n, arr):
    pairs = 0
    count = 0
    for x in arr:
        if n == x:
            count += 1
        if count == 2:
            pairs += 1
            count = 0
    return pairs

def sockMerchant(n, ar):
    count = 0
    numbers = set()
    [numbers.add(x) for x in ar]
    for x in numbers:
        count += count_elements(x, ar)
    return count