Count Unhappy Friends LeetCode solution in Python

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class Solution:
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    def unhappyFriends(
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        self, n: int, preferences: List[List[int]], pairs: List[List[int]]
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    ) -> int:
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        dd = {}
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        for i, x in pairs:
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            dd[i] = preferences[i][: preferences[i].index(x)]
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            dd[x] = preferences[x][: preferences[x].index(i)]
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        ans = 0
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        for i in dd:
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            for x in dd[i]:
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                if i in dd[x]:
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                    ans += 1
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                    break
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        return ans