OOP 8 lab 2 task

#include <iostream>

using namespace std;

int** createMatrix(int n, int m);

class Matrix {
    int n, m;
    int** data;

    friend Matrix mult(const Matrix &a, const Matrix &b);

    public:
        Matrix () {}

        Matrix(int x, int y) : n(x), m(y) { data = createMatrix(n, m); }

        Matrix operator * (const Matrix &x) { return mult(*this, x); }

        void get(char c);

        void set(char c);
};

int main() {
    int an, am, bn, bm;

    cout << "Enter size of matrix A: ";
    cin >> an >> am;

    cout << "Enter size of matrix B: ";
    cin >> bn >> bm;

    Matrix a(an, am), b(bn, bm);

    a.set('A');
    b.set('B');

    Matrix c;

    c = a * b;

    c.get('C');

    return 0;
}

Matrix mult(const Matrix &a, const Matrix &b) {
    int n = a.n,
        m = b.m;
    int sum;

    if (a.m != b.n) {
        exit(1);

        cout << "Error" << endl;
    }

    Matrix c(n, m);

    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {
            sum = 0;

            for (int k = 0; k < a.m; k++) {
                sum += a.data[i][k] * b.data[k][j];
            }

            c.data[i][j] = sum;
        }
    }

    return c;
}

int** createMatrix(int n, int m) {
    int** matrix = new int* [n];

    for (int i = 0; i < n; i++) {
        matrix[i] = new int [m];
    }

    return matrix;
}

void Matrix :: set(char c) {
    cout << "Enter matrix " << c << " [" << n << "x" << m << "]:" << endl;

    for (int i = 0; i < n; i++) {
        cout << "\t";
        for (int j = 0; j < m; j++) {
            cin >> data[i][j];
        }
    }

    return;
}

void Matrix :: get(char c) {
    cout << "Matrix "<< c << " [" << n << "x" << m << "]:" << endl;

    for (int i = 0; i < n; i++) {
        cout << "\t";
        for (int j = 0; j < m; j++) {
            cout << data[i][j] << " ";
        }
        cout << endl;
    }

    return;
}