remove_if help!!

[dupdupdup]

i would like to know how to remove an object from a list base on a condition?

Class A
{
   public:
          A(int x,int y);
          int x;
          int y;
};


int main()
{
     list<A> listA;

A lista1(123,32);
listA.push_back(lista1);
A lista2(3123,1233);
listA.push_back(lista2);
A lista3(123,4123);
listA.push_back(lista3);

//HERE HOW TO REMOVE LIST if x = 123?
listA.erase(remove_if(listA.begin(),listA.end(),/*REMOVE CRITERIA*/);
}