Lonely Integer

 1 def main():
 2     n = int(raw_input())
 3     s = dict()
 4     a = 0
 5 
 6     arr = map(int,raw_input().strip().split())
 7     for _ in range(n):
 8         num = arr[_]
 9         if not s.get(num):
10             s.update({num:1})
11         else:
12             a = s.get(num)
13             a += 1
14             s.update({num:a})
15 
16     for i in s:
17         if s.get(i) % 2 != 0:
18             print i
19             break
20 
21 main()

1 #!/usr/bin/py
2 def lonelyinteger(a):
3     answer = 0
4     answer = reduce(lambda x,y: x^y, a)
5     return answer
6 if __name__ == ‘__main__‘:
7     a = input()
8     b = map(int, raw_input().strip().split(" "))
9     print lonelyinteger(b)