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You are to calculate the diagonal disproportion of a square matrix. The diagonal disproportion of a square matrix is the sum of the elements of its main diagonal minus the sum of the elements of its collateral diagonal. The main and collateral diagonals of a square matrix are shown in figures 1 and 2 respectively.
The elements of the main diagonal are shown in green in figure 1, and the elements of the collateral diagonal are shown in cyan in figure 2.
Given a String[] matrix, return its diagonal disproportion. The j'th character of the i'th element of matrix should be treated as the element in the i'th row and j'th column of the matrix.
