4-5

#include <iostream.h>class Matrix{public:Matrix();friend Matrix operator +(Matrix &,Matrix &);friend istream& operator >>(istream &,Matrix &);friend ostream& operator <<(ostream &,Matrix &);private:int mat[2][3];};Matrix::Matrix(){ for(int i=0;i<2;i++) for(int j=0;j<3;j++) mat[i][j]=0;}Matrix operator +(Matrix &a,Matrix &b){ Matrix c; for(int i=0;i<2;i++) for(int j=0;j<3;j++) c.mat[i][j]=a.mat[i][j]+b.mat[i][j]; return c;}istream & operator >>(istream & in,Matrix &c){ for(int i=0;i<2;i++) for(int j=0;j<3;j++) in>>c.mat[i][j]; return in;}ostream & operator <<(ostream & out,Matrix &c){ for(int i=0;i<2;i++) for(int j=0;j<3;j++) {     out<<c.mat[i][j]<<" "; cout<<endl; } return out;}int main(){ Matrix a,b,c; cin>>a; cout<<a; cin>>b; cout<<b; c=a+b; cout<<c; return 0;}