#include <bits/stdc++.h>
using namespace std;
 
once_flag flg;
class SingleTon
{
	static SingleTon* pInstance ;
	SingleTon(){} 
	SingleTon& operator=(const SingleTon& a){} 
	SingleTon(const SingleTon& a){}
	int val ;
	public :
	static SingleTon* getInstance()
	{
		if(pInstance==nullptr)
		{
			call_once(flg , [](){pInstance = new SingleTon(); }) ;
		}
		return pInstance;
	}
	void SetVal(int i){ val = i ;}
	int GetVal(){return val;}
};
 
SingleTon* SingleTon::pInstance = 0; 
 
int main() {
	// your code goes here
	SingleTon::getInstance()->SetVal(10);
	cout << SingleTon::getInstance()->GetVal();
 
 
	return 0;
}

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