print(len(list(filter(lambda x:x%2!=0,[sum(int(i) for i in bin(j)[2:]) for j in range(10000)]))))
'''
⚠️Challenge: how many odious numbers smaller than 10.000 can you find⚠️
odious numbers are non-negative numbers that have an odd number of ones in the binary expansion
# 21 = 10101 = 3
# 50 = 110010 = 3
Challenge: how many odious numbers smaller than 10.000 can you find?
'''
