2023/5/26

#include <iostream>
#include<bits/stdc++.h>
using namespace std;
template<class T>
double dist(T a, T b)
{
    return a-b;
}
class Complex{
    private:
        double real,imag;
        public:
            Complex(double r=0,double i=0){
                real=r;imag=i;
            }
            double operator-(Complex c){
                return sqrt((real-c.real)*(real-c.real)+(imag-c.imag)*(imag-c.imag));
            }
            
};
int main()
{        
    //cout<<dist<int>(2,9);
    Complex c1(1,2);
    Complex c2(8,8);
    cout<<dist<Complex>(c1,c2);
    return 0;
}