How does C + + clear the last output?

#include <iostream.h>
#include <stdlib.h>
int main () {
cout<< "PBY PBY PBY PBY PBY";

cout<< "PBY PBY PBY PBY PBY";
System ("CLS"); Is here, I want to clear the last time (second)
Input "" "PBY PBY PBY PBY" PBY ",
But it cleared the whole screen .... = = ....
Cin.get (): Cin.get ();
return 0;
}//Ask the expert to answer the!!!!!

There is no line break that seems to be able to move one box through the output of a "\b" before and after a few more outputs can move a few more cells. Move to the front and then output the space to cover the original position.

How does C + + clear the last output?