program capso;
uses crt;
var n,x:integer;
function ktnt(k:integer):boolean;
var l:integer;
begin
ktnt:=false;
if k<2 then exit;
for l:=2 to trunc(sqrt(k)) do
if k mod l=0 then exit;
ktnt:=true;
end;
BEGIN
clrscr;
write('Nhap n: '); readln(n);
writeln('Cap so x,y thoa man la: ');
for x:=2 to n div 2 do
if ktnt(x) and ktnt(n-x) then writeln(x,' ',y);
readln
end.
Bài 2:
program xuathien;
var A:array[1..100] of integer;
n,i,max,j,d,ptu:integer;
begin
clrscr;
write('Nhap so luong phan tu n: '); readln(n);
for i:=1 to n do
begin
write('A[',i,']= '); readln(A[i]);
end;
max:=1; ptu:=A[i];
for i:=1 to n-1 do
begin
d:=0;
for j:=1 to n do
if A[j]=A[i] then d:=d+1;
if d>max then
begin
max:=d;
ptu:=A[i];
end;
end;
writeln(ptu,' la gia tri xuat hien nhieu nhat trong day');
write('Cac vi tri xuat hien cua ',ptu,' la: ');
for i:=1 to n do
if A[i]=ptu then write(i,' ');
readln
end.
