import java.util.Scanner; import java.util.Stack; // 注意类名必须为 Main, 不要有任何 package xxx 信息 public class Main { private static class Matrix { int x; int y; //相乘后的矩阵 public static Matrix matrixMulti(Matrix a, Matrix b) { int x = a.x; int y = b.y; return new Matrix(x, y); } public static int sum(Matrix a,...