B3)
program TinhTongBinhPhuong;
var
  A: array[1..100] of integer;
  N, K, i, sum: integer;
begin
  write('Nhap so phan tu cua day A: ');
  readln(N);
  
  write('Nhap cac phan tu cua day A: ');
  for i := 1 to N do
  begin
    read(A[i]);
  end;
  
  write('Nhap so K: ');
  readln(K);
  
  sum := 0;
  for i := 1 to N do
  begin
    if A[i] <> K then
      sum := sum + sqr(A[i]-K);
  end;
  
  writeln('Tong binh phuong cac so khac K: ', sum);
  
  readln;
end.

B4)
program XoaKyTu;
var
  s, s_new: string;
  ch: char;
  i: integer;
begin
  write('Nhap xau s: ');
  readln(s);
  
  write('Nhap ky tu ch: ');
  readln(ch);
  
  s_new := '';
  for i := 1 to length(s) do
  begin
    if s[i] <> ch then
      s_new := s_new + s[i];
  end;
  
  writeln('Xau moi: ', s_new);
  
  readln;
end.