add number

// io.cpp
#include <iostream>

int readNumber()
{
    std::cout << "Enter a number: ";
    int x;
    std::cin >> x;
    return x;
}

void writeAnswer(int x)
{
    std::cout << "The answer is: " << x << std::endl;
}

// main.cpp
int readNumber();
void writeAnswer(int x);

int main()
{
    int x = readNumber();
    int y = readNumber();
    writeAnswer(x + y);
    return 0;
}