Resolve UART Namespaces

#include <iostream>
using namespace std;

// Create namespace Boot with nested namespace UART
// Create namespace App  with nested namespace UART
namespace Boot {
    namespace UART {
        void send() {
            cout << "BOOT UART";
        }
    }
}

// Application UART driver
namespace App {
    namespace UART {
        void send() {
            cout << "APP UART";
        }
    }
}
int main() {
    int mode;
    cin >> mode;

    if (mode == 1) {
        Boot::UART::send();
    }
    else if (mode == 2) {
        App::UART::send();
    }

    return 0;
}

Solving Approach