#include <iostream>
#include <bits/stdc++.h> 
using namespace std;
 
int main() {
	// your code goes here
	unordered_set <int> numbers;
	numbers.insert(10);
	numbers.insert(20);
	numbers.insert(30);
	numbers.insert(40);
 
	cout << "total numbers of 10s are : " << numbers.count(10) << endl;
	cout << "size of entire set is : " << numbers.size() << endl;
 
	// travesing set using iterator.
	cout << "printing entire set" << endl;
	for( auto itr = numbers.begin(); itr != numbers.end(); itr++  )
	{
		cout << *itr << endl;
	}
 
	numbers.erase(10);
	// erasing element.
	cout << "set after erasing 10" << endl ;
	for( auto itr = numbers.begin(); itr != numbers.end(); itr++  )
	{
		cout << *itr << endl;
	}
 
	unordered_set <int>::iterator itr = numbers.find(10);
 
	itr = numbers.find(20);
	if( itr != numbers.end() )
	{
		cout << "element is found :" << endl;
		cout << *itr << endl;	
		cout << "the index number is : " << std::distance(numbers.begin(), itr ) << endl;
	}
	else
	{
		cout << "element not found "<< endl;
	}
 
	itr = numbers.find(10);
	if( itr != numbers.end() )
	{
		cout << "element is found : " << endl;
		cout << *itr << endl;
	}
	else
	{
		cout << "element not found" << endl;
	}
 
	return 0;
}