write a c++ program to consider the class matrix

/*write a c++ program to consider the class matrix
class matrix
{
int a[3][3];
public:\\method;
};
overload the -(unary) should negate the number stored in the object.
*/
#include<iostream.h>
#include<conio.h>
class matrix
{
    int a[3][3];
public:    void accept();
    void display();
    void operator -();
    };
void matrix::accept()
{
    int i,j;
        for(i=0;i<3;i++)
    {
        for(j=0;j<3;j++)
        {
            cin>>a[i][j];
        }
    }
}
void matrix::display()
{
    int i,j;
    for(i=0;i<3;i++)
    {
        cout<<"\n";
        for(j=0;j<3;j++)
        {
            cout<<"\t"<<a[i][j];
        }
    }
    cout<<"\n";
}
void matrix ::operator -()
{
int i,j;
for(i=0;i<3;i++)
{
for(j=0;j<3;j++)
{
a[i][j]=-a[i][j];
}
}
}
int main()
{
    clrscr();
    matrix m;
    cout<<"Enter the matrix :";
    m.accept();
    -m;
    cout<<"\narray after negation is\n";
    m.display();
    getch();
    return 0;
}
/*
Enter the matrix :
1 2 3
7 4 1
9 6 3

array after negation is

    -1      -2      -3
    -7      -4      -1
    -9      -6      -3

*/