Easy Python Solution
\n# Code\n\nclass Solution:\n    def diagonalSum(self, mat: List[List[int]]) -> int:\n        su=0\n        n = len(mat)\n        for i in range(n):\n          
\n# Code\n```\nclass Solution:\n    def diagonalSum(self, mat: List[List[int]]) -> int:\n        su=0\n        n = len(mat)\n        for i in range(n):\n            su+=mat[i][i]\n            su+=mat[i][n-1-i]\n        if n%2==1:\n            su-=mat[n//2][n//2]\n        return su\n```
['Python3']