#include <iostream.h>
 
#include <fstream.h>
 
main(int argc, char *argv[]) 
{
//definition of the variables.
 
int mtx1[20][20], mtx2[20][20], mtx3[20][20];
 
int n, i, j, k;
 
//exit if the number of arguments is not 2.
 
if(argc != 3)
{
 
 
cerr << "Usage: mm <filename1> <filename2>\n";
 
return 1;
 
}
 
//open the input file 1. exit if an error occurs.
 
ifstream fin1(argv[1]);
 
if(!fin1) {
 
cerr << "Can't open file1!\n";
 
return 1;
 
}
 
 
//read the input file 1.
 
fin1 >> n; //read the number of rows and columns.
 
 
for(j=1; j<=n; j++) {
 
 
for(i=1; i<=n; i++) {
 
 
fin1 >> mtx1[i][j]; //read the elements of the matrix.
 
 
}
 
}
 
fin1.close(); //close the file 1.
 
//open the input file 2. exit if an error occurs.
 
ifstream fin2(argv[2]);
 
if(!fin2) {
 
cerr << "Can't open file2!\n";
 
return 1;
 
}
 
fin2 >> n; //read the number of rows and columns.
 
for(j=1; j<=n; j++) {
 
for(i=1; i<=n; i++) {
 
fin2 >> mtx2[i][j]; //read the elements of the matrix.
 
}
 
}
 
fin2.close(); //close the file 2.
 
//fill the matrix 3 for the result with zero.
 
for(j=1; j<=n; j++) {
 
 
for(i=1; i<=n; i++) {
 
 
mtx3[i][j] = 0;
 
 
}
 
}
 
//multiply the matrices.
 
for(j=1; j<=n; j++) {
 
 
for(i=1; i<=n; i++) {
 
 
for(k=1; k<=n; k++) {
 
 
mtx3[i][j] += mtx2[i][k] * mtx1[k][j];
 
 
}
 
}
 
}
 
//output the result.
 
cout << n << "\n";
 
for(j=1; j<=n; j++) {
 
 
for(i=1; i<=n; i++) {
 
 
cout << mtx3[i][j];
 
 
if(i < n) {
 
 
cout << "\t";
 
 
}
 
}
 
cout << "\n";
 
}
 
return 0;
 
} //end of the program.