#include <iostream>

namespace ad{
    int cal(int a,int b){
        int res=a+b;
        return res;
    }

    int cal(int a){
        int res=a+a;
        return res;
    }
}

int main() {
    //using namespace std;
    //or using std::cal;
    //or using std::cin or std::cout;
    
    int a = 10;
    int b = 5;
    int res = ad::cal(a+b);
    std::cout << res << std::endl;
}

/*
namespace or library we can call
A namespace in programming is like a container or a space where you can put related code and variables to 
organize and prevent naming conflicts.

Imagine you have a bunch of toys, and you want to keep your toy cars separate from your toy action figures.
    You might use two different boxes, one labeled "Toy Cars" and the other labeled "Action Figures,"
    to keep them organized. In this analogy:

The boxes are like namespaces.
The toy cars and action figures are like code and variables.
In programming:

A namespace helps keep code organized by grouping related code and variables together.
It prevents naming conflicts because you can have the same variable or function name in different namespaces 
without them interfering with each other.
So, namespaces are used to:

Organize Code: They help make your code more structured and easier to manage by grouping related code 
together.

Avoid Naming Conflicts: They prevent situations where two pieces of code accidentally use the same name for
    different things, which can lead to errors.

For example, you might have a "Math" namespace with all your math-related functions and variables and a 
"Graphics" namespace with graphics-related code. This way, you can use common names like "calculate" in
    both namespaces without any confusion or conflict.
*/