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class Solution:
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    def surfaceArea(self, grid: List[List[int]]) -> int:
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        m, n = len(grid), len(grid[0])
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        area = 0
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        for r in range(m):
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            for c in range(n):
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                if grid[r][c] != 0:
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                    area += 2
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                if r == 0 or r == m - 1:
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                    area += grid[r][c] if m != 1 else 2 * grid[r][c]
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                if r != m - 1:
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                    area += abs(grid[r][c] - grid[r + 1][c])
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                if c == 0 or c == n - 1:
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                    area += grid[r][c] if n != 1 else 2 * grid[r][c]
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                if c != n - 1:
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                    area += abs(grid[r][c] - grid[r][c + 1])
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        return area