#include <iostream>
using namespace std;

class DivByZeroEx {
public:
  DivByZeroEx() : m_message( "divide by zero" ) {}
  string what() { return m_message; }
private:
  string m_message;
};
  

double quotient(int num, int den) {
  if (den == 0) 
    throw DivByZeroEx();
  return static_cast<double>(num) / den; 
}

int main() {
  try {
    cout << quotient(7, 0) << endl;
  } 
  catch (DivByZeroEx& e) {
    cout << e.what() << endl;
  }
  return 0;
}