#include <iostream>
#include <cstdlib>
#include <ctime>
using namespace std;
 
char randChar()
{
	static char pool[]="ABCDEFGHIJKLMNOPRSTUWXYZ";
	return pool[rand()%(sizeof(pool)-1)];
}
 
char randDigit()
{
	static char pool[]="0123456789";
	return pool[rand()%(sizeof(pool)-1)];
}
 
string kodowanie()
{
	return string {{ randChar(),randChar(),randDigit(),randDigit() }};
}
 
int main()
{
	srand(time(0));
	cout<<kodowanie()<<endl;
    return 0;
}

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