You want to see and rewrite values defined in one class in more than one different class

This is Unity's C#.

public class A {
    public int[]tmp = new int[3] {1,2,3}
}

class called

public class AddScript:MonoBehavior {
    Aa = new A();
    void Start() {
        a.tmp[0]++;
    }

When called by Script attached to GameObject (prefabbed and multiple-regenerated), tmp is initialized each time a GameObject is generated, and tmp[0] remains at 1.
How do I increase the value of tmp[0] each time it is generated?