python 素数解法

def prime_num(n):
i=2
while i<n:
if n%i == 0:
return False
i=i+1
return True

if name == 'main':
while True:
try:
s = input()
# flag = prime_num(s)
i = int(s/2)
while i<s:
if prime_num(i) and prime_num(s-i):
print s-i
print i
break
i=i+1
except:
break