Why Operator overloading behaves so strange

Hello Friend the output of the below program is so strange. I am not getting the reason.

#include <iostream>
 using namespace std;
 
 class xyz
 {
     private:
     int ab, cd;
     public:
     xyz()
     {
 
     }
     xyz(int i, int j)
     {
         ab = i;
         cd = j;
 
     }
     xyz operator+(xyz);
     void show()
     {
         cout << ab << " ....  "<< cd;
     }
 
 };
 xyz xyz :: operator +(xyz ob)
 {
     xyz temp;
     temp.ab = ab + temp.ab;
     temp.cd = cd + temp.cd;
     return temp;
 }
 
 int main()
 {
    // xyz xy, yz;
 
    xyz xy(2, 3);
    xyz yz(4, 5);
     xy = xy + yz;
 
     xy.show();
     return 0;
 }
 

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