from random import shuffle

def test(x,f,to_n=100000):
    suc = 0
    for i in xrange(0,to_n):
        shuffle(x)
        if f(x): suc+=1
    return float(suc)/float(to_n)

def one_got_same_color(a):
    for i in range(0,len(a),2):
        if a[i]==a[i+1]: return True
    return False

#The following will simulate what's the probability for the
#first kid to recieve a red ball or a blue ball
#print test([1,1,2,2,3,3,4,4],lambda x: x[0]==1 and x[1]==2)
print test([1,1,2,2,3,3,4,4],one_got_same_color)