c++ program for address and variables : the output for this code is : 

>9

and i'm not sure what does it change in the function add1
and also what does this &n mean and what it do when we assign the **i** to **&n**

    #include <iostream>
    using namespace std;

    int add1(int &n){

	n++;

	return n;
    }

    int main(){
	int m = 0;

	for (int i = 0; i < 5; i++){
		m += add1(i);

		
	}
	cout << m ;

	cout << "\n\n";


	return 0;
    }
