/// declaring function prototypes
#include <iostream>

using namespace std;

void odd (int x);
void even (int x);

int main()
{

    int i;

    do {
        cout << "Please enter number (0 to exit program): ";
        cin >> i;
        odd(i);
    }while(i != 0);

    return 0;

} /// end main
void odd (int x) {

    if((x%2) != 0)
        cout << "It is odd." << endl;
    else
        even(x);

}
///==================================
void even (int x) {

    if((x%2) == 0)
        cout << "It is even." << endl;
    else odd(x);

}
///==================================