for (i = 0; i < k; ++i)
    for (j = 0; j < p; ++j)
    {
        cout << "Podaj element macierzy B: kolumna " << i + 1 << " wiersz " << j + 1 << endl;
        cin >> B[i][j];
    }


float iloczyn = 0;
if (a > m || b > k || a < 1 || b < 1 || n != p)
{
    cout << "Podany wersz lub kolumna nie istnieja!" << endl;
}
else
{
    for (i = 0; i < n; ++i)
        iloczyn += A[a - 1][i] * B[i][b - 1];
    cout << "loczyn skalarny wynosi: " << iloczyn << endl;
}



cout << "Elementy macierzy C, gdzie C=A*B: " << endl;
for (i = 0; i < m; ++i)
    for (j = 0; j < k; ++j)
    {
        iloczyn = 0;
        for (int z = 0; z < n; ++z)
            iloczyn += A[i][z] * B[z][j];
        C[i][j] = iloczyn;
    }