Change 1 -> 0 no conditionals, negation, bit operators

// Change 0 to 1 or 1 to 0.
// Not allowed: conditionals, booleans, bit operators

#include <iostream>
#include <cctype>
#include <string>

using namespace std;

// This function changes a 0 to a 1 or
// a 1 to a 0, without using
// conditionals, negation or bit operators
int flip(int zero_or_one)
{
    int flipped_number = 0; // The result of the flip.

    flipped_number = 1 - zero_or_one; // Flip the number.
    return flipped_number; // Return the result.
}

int main()
{
    string one_or_zero; // User input.
    int result = 0; // Output after flip.

    cout << "Enter 1, and you will receive 0.\n"
        "Enter 0, and you will receive 1.\n"
        "Your entry: ";
    getline(cin, one_or_zero); // Get user input.
    // If the user did not enter a 1 or a 0,
    while (one_or_zero.compare("0") != 0 && one_or_zero.compare("1") != 0)
    {
        cout << "You must enter 1 or 0.\n"
            "Your entry: ";
        cin >> one_or_zero; // Get new input.
    }

    result = flip(stoi(one_or_zero)); // Flip the number.

    cout << result << '\n'; // Display the result.

    return 0; // End the program.
}