Вылетает необрабатываемая ошибка

class Matrix{
private:
    int** v;
    int size;
    Matrix merge(Matrix c11, Matrix c12, Matrix c21, Matrix c22){
        Matrix m(size);
        int cursize = size/2;
        for(int i = 0; i < cursize; i++){
            for(int j = 0; j < cursize; j++){
                m(i, j) = c11(i,j);
                m(i+cursize,j) = c21(i, j);
                m(i,j+cursize) = c12(i, j);
                m(i+cursize,j+cursize) = c22(i, j);
            }
        }
        return m;
    }
public:
    static bool added;
    Matrix() : size(0){}
    Matrix(int s) : size(s){
        v = new int*[size];
        for(int i = 0; i < size; i++){
            v[i] = new int[size];
        }
    }

    Matrix(Matrix m, const int index1, const int index2){
        size = m.size/2;
        v = new int*[size];
        for(int i = 0; i < size; i++){
            v[i] = new int[size];
        }
        for(int i = index1; i-index1<size; i++ ){
            for(int j = index2; j -index2<size; j++){
                int item= m(i, j);
                v[i-index1][j-index2]=item;
            }
        }
    }
    void getMatrix(){
        int n = size;
        if(n%2!=0){
            size++;
            added = true;
        }
        v = new int*[size];
        for(int i = 0; i < size; i++){
            v[i] = new int[size];
        }
        for(int i = 0; i < n; i++){
            for(int j = 0; j < n; j++){
                v[i][j] = rand()%100;
            }
        }
    }
    void display() const{
        int n = added? size-1: size;
        for(int i = 0; i <n; i++){
            for(int j = 0; j<n; j++){
                cout << v[i][j] << " ";
            }
            cout << endl;
        }
    }
    int& operator()(const int index1,const int index2){
        return v[index1][index2];
    }

    Matrix operator+(Matrix m){
        Matrix r(size);
        for(int i = 0; i < size; i++){
            for(int j = 0; j < size; j++){
                r(i,j)= v[i][j] + m(i, j);
            }
        }
        return r;
    }
    Matrix operator-(Matrix m){
        Matrix r(size);
        for(int i = 0; i<size; i++){
            for(int j = 0; j< size; j++){
                r(i, j) = v[i][j]-m(i, j);
            }
        }
        return r;
    }
    Matrix simpleMultiplication(Matrix m){
        Matrix res(size);
        int prom = 0;
        for(int i = 0; i <size; i++){
            for(int j = 0; j < size; j++){
                for(int k = 0; k<size; k++){
                    prom+= v[i][k] * m(k, j);
                }
                res(i, j) = prom;
            }
        }
        return res;
    }
    Matrix operator*(Matrix B){
        if(size == 1){
            Matrix m(size);
            m(0,0) = v[0][0] * B(0, 0);
            return m;
        }
        // init of base matrixes
        Matrix A11(*this, 0, 0);
        Matrix A12(*this, 0, size/2);
        Matrix A21(*this, size/2, 0);
        Matrix A22(*this, size/2, size/2);
        Matrix B11(B, 0, 0);
        Matrix B12(B, 0, size/2);
        Matrix B21(B, size/2, 0);
        Matrix B22(B, size/2, size/2);
        // end of init
        //prom matrixes S
        Matrix s1 = A21 + A22;
        Matrix s2 = s1 - A11;
        Matrix s3 = A11 - A21;
        Matrix s4 = A12 - s2;
        Matrix s5 = B12 - B11;
        Matrix s6 = B22 - s5;
        Matrix s7 = B22 - B12;
        Matrix s8 = s6 - B21;
        // end of prom matrixes
        Matrix p1 = s2 * s6;
        Matrix p2 = A11 * B11;
        Matrix p3 = A12 * B21;
        Matrix p4 = s3 * s7;
        Matrix p5 = s1 * s5;
        Matrix p6 = s4 * B22;
        Matrix p7= A22 *s8;

        Matrix t1 = p1+p2;
        Matrix t2 = t1+p4;

        Matrix c11 = p2+p3;
        Matrix c12 = t1+p5+p6;
        Matrix c21 = t2 - p7;
        Matrix c22 = t2 + p5;
        return merge(c11, c12, c21, c22);
    }
};

class Test{
private:
    int matrixSizes[6] = {4, 16, 32, 64,128,256};

public:
    void getTests(){
        for(int size : matrixSizes){
            clock_t average1 = 0;
            clock_t average2 = 0;

            for(int i = 0; i < 1; i++) {
                Matrix m1(size);
                m1.getMatrix();
                Matrix m2(size);
                m2.getMatrix();
                clock_t start1 = clock();
                Matrix m = m1*m2;
                clock_t finish1 = clock() - start1;
                clock_t start2 = clock();
                m = m1.simpleMultiplication(m2);
                clock_t finish2 = clock() - start2;
                average1+=finish1;
                average2+=finish2;
             }
            cout << "For size of matrix: " << size << endl;
            cout <<"Time in seconds for shtrassen alghoritm: " << average1*1.0/CLOCKS_PER_SEC << endl;
            cout <<"Time in seconds for simple alghoritm: " << average2*1.0/CLOCKS_PER_SEC << endl;
        }
    }
};
bool Matrix::added = false;
int main() {
    Test t;
    t.getTests();
    return 0;
}

Не знаю ответит ли кто, моя проблема что на тесте когда размер матрицы 256 вылетает необрабатываемая ошибка и я не могу даже догадаться почему.