```
class Solution(object):
def findTheDifference(self, s, t):
dict1 = {}
dict2 = {}
for i in s:
if i not in dict1:dict1[i] = 0
dict1[i] +=1
for j in t:
if j not in dict2:dict2[j] = 0
dict2[j] +=1
for i in dict2:
try:
if dict2[i] !=dict1[i]:
return i
except:
return i
```