MATRICA C++

#include <iostream>
#include <cstring>
using namespace std;
class Matrica{
private:
float matrix[10][10];
int rows;
int columns;
public:
Matrica(){}
Matrica(int rows,int columns){
this->rows=rows;
this->columns=columns;
for(int i=0;i<rows;i++){
for(int j=0;j<columns;j++){
this->matrix[i][j]=0;
}
}
}
friend istream& operator>>(istream &input,Matrica &m){
input>>m.rows>>m.columns;
for(int i=0;i<m.rows;i++){
for(int j=0;j<m.columns;j++){
input>>m.matrix[i][j];
}
}
return input;
}
friend ostream& operator<<(ostream &output,Matrica &m){
for(int i=0;i<m.rows;i++){
for(int j=0;j<m.columns;j++){
output<<m.matrix[i][j]<<" ";
}
output<<endl;
}
return output;
}
Matrica& operator+(int a){
for(int i=0;i<rows;i++){
for(int j=0;j<columns;j++){
matrix[i][j]+=a;
}
}
return *this;
}
Matrica& operator-(Matrica &b){
for(int i=0;i<rows;i++){
for(int j=0;j<columns;j++){
this->matrix[i][j]-=b.matrix[i][j];
}
}
return *this;
}
Matrica operator*(Matrica &b){
Matrica newmatrica(this->rows,this->columns);
for(int i=0;i<rows;i++){
for(int j=0;j<columns;j++){
for(int k=0;k<columns;k++){
newmatrica.matrix[i][j]+=this->matrix[i][k]*b.matrix[k][j];
}
}
}
return newmatrica;
}
};
int main()
{
Matrica A,B,C;
cin>>A>>B>>C;
Matrica D=B*C;
Matrica R=A-D+2;
cout<<R;
}