import java.io.*;

public class MatrixDemo
{
   double[][] data;
   int nrows = 0;
   int ncols = 0;

   MatrixDemo (int m, int n)
   {
      data = new double[m][n];
      nrows = data.length;
      ncols = data[0].length;
   }
      
   public MatrixDemo addMatrices (MatrixDemo b)
   {
      if (b.nrows == nrows && b.ncols == ncols)
      {
         MatrixDemo result = new MatrixDemo(nrows, ncols);
         for (int i=0; i<nrows; i++)
            for (int j=0; j<ncols; j++)
                result.data[i][j] = data[i][j] + b.data[i][j];
         return result;
      } else 
          return null; 
   }

   public MatrixDemo multipleMatrices (MatrixDemo b)
   {
      if (b.nrows == ncols)
      {
         MatrixDemo result = new MatrixDemo(nrows, b.ncols);
         for (int i=0; i<nrows; i++)
            for (int j=0; j<b.ncols; j++)
               for (int k=0; k<ncols; k++)
                   result.data[i][j] += data[i][k] * b.data[k][j];
         return result;
      } else 
          return null; 
   }

   public void print ()
   {
      for (int i=0; i<nrows; i++)
      {
         for (int j=0; j<ncols; j++)
            System.out.print (data[i][j] + "  "); 
         System.out.print ("\n");
      }
   }
}