*for ... do
program songto;
uses crt;
var i,n,d:integer;
begin
clrscr;
write('Nhap so can kiem tra: '); readln(n);
if n<2 then write(n,' khong phai so nguyen to')
else
begin
d:=0;
for i:=2 to n div 2 do
if n mod i=0 then d:=d+1;
if d=0 then write(n,' la so nguyen to')
else write(n,' khong phai so nguyen to');
end;
readln;
end.
*while ... do
program kiemtrangto;
uses crt;
var n,i:integer;
begin
clrscr;
write('Nhap so can kiem tra: '); readln(n);
if n<2 then write(n,' khong phai so nguyen to')
else
begin
i:=2;
while n mod i<>0 do i:=i+1;
if n=i then write(n,' la so nguyen to')
else write(n,' khong phai so nguyen to');
end;
readln;
end.
