vector = [1,1,0,0,0,0,1,1,1,1,1,0,0,0,0,0,1,0,0,0,1,0,0,1,1,0,0,1,1,1,0,0,1,1,1,1,1,1,1,0,0,1,0,1,0,1,1,1,1,1,1,1]
threshold = 20

print vector

count_i = 0

while count_i < len(vector)-1:
    symbol = vector[count_i]
    if symbol==1:
        counter = 0
        while symbol==1 and (count_i+counter) < len(vector)-1:
            counter = counter + 1
            symbol = vector[count_i+counter]
        counter2 = counter-1
        if counter <= threshold:
            while counter2 >= 0:
                  vector[count_i+counter2] = 0
                  counter2 = counter2 - 1
        count_i+=counter
    else: count_i+=1

print vector