有三个数字，两个相同，输出那个不同的【不喜勿喷】

#!/usr/bin/env python
#_*_ coding:utf-8 _*_
try:
def resu(a,b,c):
test = [a,b,c]
for i in range(3):
if i == 0:
if test[i] == test[i+1]:
print test[i+2]
exit()
if i == 1:
if test[i-1] == test[i+1]:
print test[i]
exit()
if i == 2:
if test[i] == test[i-1]:
print test[i-2]
exit()
if resu(80, 80,10):
print resu(80, 80,10)
else:
print "none"
except Exception as e:
print e