import numpy as np
values = ['2','3','4','5','6','7','8','9','10','J','K','Q','A']
suits = ['H','D','S','C']

cards = [[v,s] for v in values for s in suits]

def sim_one_pair():
    np.random.shuffle(cards)
    value_list = []
    count_taken = 0
    pair = 0
    for card in cards:
        count_taken += 1 #Count each time w
        value = card[0]
        if not value in value_list:
            value_list.append(value)
        if len(value_list) == 4: #If value list have exactly 4, it means that there is a pair.
            pair += 1
        if pair == 1: #When we get a pair, display how many times it took.
            return count_taken
    print(value_list)
sim_one_pair()