#include <iostream>

class Complex {
private:
    double real;
    double imag;

public:
    Complex(double r = 0, double i = 0) : real(r), imag(i) {}

    // 重载加法运算符
    Complex operator+(const Complex& c) {
        return Complex(real + c.real, imag + c.imag);
    }

    // 重载减法运算符
    Complex operator-(const Complex& c) {
        return Complex(real - c.real, imag - c.imag);
    }

    friend std::ostream& operator<<(std::ostream& out, const Complex& c) {
        out << c.real;
        if (c.imag >= 0) {
            out << "+i" << c.imag;
        } else {
            out << "-i" << -c.imag;
        }
        return out;
    }
};

int main() {
    Complex a(2, 5), b(7, 8), c(0, 0);

    // c=a+b
    c = a + b;
    std::cout << c << std::endl;

    // c=4.1+a
    c = Complex(4.1, 0) + a;
    std::cout << c << std::endl;

    // c=b-5.6
    c = b - Complex(5.6, 0);
    std::cout << c << std::endl;

    return 0;
}