Nested Namespace Declaration

#include <iostream>
using namespace std;

namespace Config 
{
    namespace ADC 
    { 
        int resolution = 12; 
    }
    namespace PWM 
    { 
        int frequency = 1000; 
    }
}
using namespace Config;
int main() {
    cout << "ADC.resolution="<<ADC::resolution<<"\n";
    cout << "PWM.frequency="<<PWM::frequency<<"\n";
    
    return 0;
}