program tim_so_nguyen_to_trong_xau_t;
uses crt;
function is_prime(n: integer): boolean;
var
i: integer;
begin
if n <= 1 then
begin
is_prime := false;
exit;
end;
if n <= 3 then
begin
is_prime := true;
exit;
end;
if n mod 2 = 0 then
begin
is_prime := false;
exit;
end;
for i := 3 to trunc(sqrt(n)) do
begin
if n mod i = 0 then
begin
is_prime := false;
exit;
end;
end;
is_prime := true;
end;
var
T: string;
i, number, max_prime: integer;
begin
clrscr;
write('Nhap xau T: ');
readln(T);
max_prime := 0;
for i := 1 to length(T) do
begin
if (T[i] >= '0') and (T[i] <= '9') then
begin
number := strToInt(T[i]);
if is_prime(number) then
begin
write(number, ' ');
if number > max_prime then
begin
max_prime := number;
end;
end;
end;
end;
writeln();
writeln('So nguyen to lon nhat trong xau T la: ', max_prime);
readln;
end.
