program ghep_Xau;
uses crt;
var
  A,B: string[50];
begin
  clrscr;
  writeln(' nhap xau A: '); readln(A);
  writeln(' nhap xau B: '); readln(B);
  writeln('Xau ', A, ' ghep voi xau ',B,': ',A+B );
  Readln;
end.		
	
program Xoa_Xau;
uses crt;
var
  A: string[50];
begin
  clrscr;
  writeln(' nhap xau A: '); readln(A);
  delete(A,4,3);
  writeln('ket qua xau A: ',A );
  Readln;
end.

program chen_Xau;
uses crt;
var
  A,B: string[50];
begin
  clrscr;
  writeln(' nhap xau A: '); readln(A);
  writeln(' nhap xau B: '); readln(B);
  insert(A,B,4);
  writeln('ket qua xau B: ',B );
  Readln;
end.