[Python] Easy solution using counter and split, 5-6 lines
\nc = Counter(A.split() + B.split())\nres = []\nfor i in c:\n\tif c[i] == 1:\n\t\tres.append(i)\n\nreturn res\n
```\nc = Counter(A.split() + B.split())\nres = []\nfor i in c:\n\tif c[i] == 1:\n\t\tres.append(i)\n\nreturn res\n```
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