M × N o'lchamli matrix matritsasi berilgan. Barcha elementlarining yig'indisini toping.
func matrixSum(M int, N int, matrix [][]int) int {
// ...
}
Input: M=2, N=3, matrix=[[1,2,3],[4,5,6]]
Output: 21
Input: M=3, N=2, matrix=[[10,20],[30,40],[50,60]]
Output: 210
Input: M=3, N=3, matrix=[[1,1,1],[1,1,1],[1,1,1]]
Output: 9
i) va ustunlar (j) bo'yicha.sum += matrix[i][j].