functions in OOP

It does not work like this here.

Here is what is expected by enquirers:
1. TRY first what you want to do!
2. Formulate what was done by you that looks like an issue/not working.

Try them and tell if you face issues.
Members will be more than happy to help like this.

#include<iostream>
Int sum(int,inti);
Int main()
{
Int x,y,add;
X=20;
Y=50;
Add=sum(x,y);
Cout"The sum is:"<<add<<endl;
Return 0;
}
Int sum(intx,inty);
{
Intz;
Z=x+y;
Return y;
}