Operator overloading using Template

#include "bits/stdc++.h"
using namespace std;
template < class T , class TT>
class my{
    TT a; T b, c;
    public:

    my operator-(my );
    friend ostream& operator<<(ostream &out, my &x){
        out << x.a << ' ' << x.b << ' ' << x.c;
        return out;
    }
    friend istream& operator>>(istream &in, my &x){// &x is must find out the reason why
        in >> x.a >> x.b >> x.c;
        return in;
    }

};
template < class aa , class bb>
my < aa, bb >  my < aa, bb > :: operator-(my x){
        my temp;

        temp.a = a - x.a;
        temp.b = b - x.b;
        temp.c = c - x.c;
        return temp;
}

int main(int argc, char const *argv[]){
    my < int, float > ob,ob2, ob3;
    cin >> ob >> ob2;
    ob3 = ob - ob2;
    cout << ob3 << '\n';
    return 0;
}