# Las Vegas algorithm
# An array of n≥2 elements, in which half are ‘a’s and the other half are ‘b’s.
# Find an ‘a’ in the array
# Compute the expected number of iterations

def f():
    var flag
    flag = 1
    while flag > 0:
        prob(1,1):
        	flag = 0
        else:
        	flag = 1
        tick 1