Optimizing a bunch of if?

Question

C++ / C#

string puk = SceneManager.GetActiveScene().name;
        if (puk == "Level1")
            levelNum = 1;
        if (puk == "Level2")
            levelNum = 2;
        if (puk == "Level3")
            levelNum = 3;
        if (puk == "Level4")
            levelNum = 4;
        if (puk == "Level5")
            levelNum = 5;

How it can be optimized not to write if every time?
PS something tells me that loops and arrays will come in handy here)

Answer 1

levelNum = int.Parse(puk[puk.Length - 1]);

Answer 2

levelNum = int.Parse(puk.Substring("Level".Length));

And be sure to make sure that the exception is caught in time if suddenly there is an error in the line.