for(auto e : elements) may cause one of elements to be wanted to be removed from vector

I have some classes:

struct Listenable{
    virtual void removeListener(Listener * listener) = 0;
};

class Listener{
public: //that way example is simpler
    unsigned myCode = 0;
    Listenable * subject = 0;

    Listener(unsigned myCode, Listenable * subject) 
        : myCode(myCode), subject(subject){}

    void notify(unsigned value){
        if(value == myCode){
            a->removeListener(this);
        }
    }
};

class A : public Listenable{
public: //that way example is simpler
    std::vector<Listener*> listeners;

   void fun(unsigned value){
        for(auto listener : listeners){
            b->notify(value);
        }
    }

    void removeListener(Listener * listener){
        auto it = std::find(listeners.begin(), listeners.end(), listener);
        if(it != listeners.end()){
            listeners.erase(it);
        }
    }
};

and the code:

A a;

Listener * l1 = new Listener(5, a);
Listener * l2 = new Listener(7, a);

a.listeners.push_back(l1);
a.listeners.push_back(l2);
a.notify(3); //OK
a.notify(5); //error

I get the vector iterator not incrementable error in a.notify(5).

I know that it's because when I notify the l1 listener (inside of for loop of A::fun(5)), it decides to unsubscribe (call to A::removeListener).

But how to solve this? I want to iterate throw all the listeners and notify them about an event. I cannot assume if any of them (or how many of them) will want to remove itself from the list (it can happens as a reaction to event or somewhere else). I also cannot assume which circumstances will force specific Listener to call A::removeListener(this) and when.

I could change void notify(...) to bool notify(...) where return true would mean "please, remove me". But I cannot be sure that user won't call A::removeListener(this) from the class that inherit from Listener anyway.