How to come output 3 ?

Question

#include <iostream>
using namespace std;
class A{
public: static int a;
A() {a++;}
};
int A::a=1;
void f(void){
A a;
throw string("?");
}

int main() {
A a;
try{f();}
catch(string &s){}

cout<<A::a;
return 0;
}

Answer 1

Gordie thanks :)