Multiply idz 2

#include <vector>
#include <cstddef>
#include <iostream>

using Matrix = std::vector<std::vector<long long>>;

Matrix Multiply(const Matrix& A, const Matrix& B) {
    size_t n = A.size();
    size_t m = B[0].size();
    size_t q = A[0].size();
    Matrix C(n, std::vector<long long>(m, 0));
    for (size_t i = 0; i < n; ++i) {
        for (size_t j = 0; j < m; ++j) {
            for (size_t k = 0; k < q; ++k) {
                C[i][j] += A[i][k] * B[k][j];
            }
        }
    }
    return C;
}

void Print(const Matrix& C) {
    for (const auto& line: C) {
        for (const auto& x: line) {
            std::cout << x << ' ';
        }
        std::cout << std::endl;
    }
}

int main() {
    Matrix A = {
        {1   , 0    ,-1,     0},
    {0,   1,    -4, -4},
    {1    ,2    ,-9 ,-8},
    {1  ,-12,   47, 48},
    };
    Matrix B = {
        {4  ,-1,-2  ,-1},
    {3  , 1 ,-1 ,-1},
   {-2  , 2  ,2  ,1},
   {-2  , 0 , 1  ,1},
    };
    Print(Multiply(A, B));
}