import math
def is_prime(num):
if num == 0:
return 0
if num == 1:
return 0
for p in range(2, int(round(math.sqrt(num))) + 1):
if int(round(num % p)) == 0:
return 0
return 1
lst = [4, 8, 5, 17, 9, 22, 21, 13, 18, 99]
maxp = lst[0]
for i in range(len(lst)):
if is_prime(lst[i]): # 17 5 13
if (maxp < lst[i]):
maxp = lst[i]
print(maxp)
'''
run:
17
'''