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#include <iostream>
using namespace std;
 
struct Countable {
  int count;
 
  incr() { count++; }
};
 
struct Parent {
	static int count;
 
	Parent() {
		count++;
	}
};
 
int Parent::count = 0;
 
struct Child1: public Parent {
	Child1(): Parent(), cnt() { incr(); }
	static Countable cnt;
};
 
int Child1::count = 0;
 
struct Child2: public Parent {
	Child2(): Parent() {}
	static int count;
};
 
int Child2::count = 0;
 
int main() {
	Child1 ch1;
	Child1 ch2;
	Child1 ch3;
	Child2 ch22;
	Child2 ch23;
 
	cout << Child1::count << endl;
 
	return 0;
}

prog.cpp:7:8: error: ISO C++ forbids declaration of ‘incr’ with no type [-fpermissive]
   incr() { count++; }
        ^
prog.cpp: In constructor ‘Child1::Child1()’:
prog.cpp:21:22: error: ‘Countable Child1::cnt’ is a static data member; it can only be initialized at its definition
  Child1(): Parent(), cnt() { incr(); }
                      ^~~
prog.cpp:21:35: error: ‘incr’ was not declared in this scope
  Child1(): Parent(), cnt() { incr(); }
                                   ^
prog.cpp: At global scope:
prog.cpp:25:13: error: ISO C++ does not permit ‘Parent::count’ to be defined as ‘Child1::count’ [-fpermissive]
 int Child1::count = 0;
             ^~~~~
prog.cpp:25:13: error: redefinition of ‘int Parent::count’
prog.cpp:18:5: note: ‘int Parent::count’ previously defined here
 int Parent::count = 0;
     ^~~~~~

Standard output is empty