# program to print duplicate numbers in a given list
# provided input
list = [1, 2, 1, 2, 3, 4, 5, 1, 1, 2, 5, 6, 7, 8, 9, 9]
new = [] # defining output list
# condition for reviewing every
# element of given input list
for a in list:
# checking the occurrence of elements
n = list.count(a)
# if the occurrence is more than
# one we add it to the output list
if n > 1:
if new.count(a) == 0: # condition to check
new.append(a)
print(new)