#include <iostream>

using namespace std;

void foo() {
  cout << "hello from global foo" << endl;
}

namespace A {  
  void foo() {
    cout << "hello from A foo" << endl;
  }
}

namespace B {
  void foo() {
    cout << "hello from B foo" << endl;
  }
}

namespace C {
  void foo() {
    cout << "hello from C foo" << endl;
  }
}

// this will cause an "ambiguous overloaded function error"
//using namespace B;

int main() {
  foo();
}