def mkslot(m, i, j):
    ij = j + i * 4
    return f"{m}[{ij}]"
    # return m + "xyzw"[i] + str(j + 1)

def mm(leftcalled = "l", rightcalled = "r"):
    stmts = []

    for i in range(4):
        for j in range(4):
            res = mkslot("m", i, j)
            terms = []

            for k in range(4):
                left = mkslot(leftcalled, i, k)
                right = mkslot(rightcalled, k, j)

                term = f"{left} * {right}"
                terms.append(term)

            stmt = f"{res} = {' + '.join(terms)};"
            stmts.append(stmt)

    return "\n".join(stmts)

print(mm())