Câu 1:
uses crt;
var a:array[1..100]of integer;
kt:boolean;
n,i,ln,j:integer;
begin
clrscr;
readln(n);
for i:=1 to n do readln(a[i]);
ln:=0;
for i:=1 to n do
if a[i]>1 then
begin
kt:=true;
for j:=2 to trunc(sqrt(a[i])) do
if a[i] mod j=0 then kt:=false;
if kt=true then
begin
if ln<a[i] then ln:=a[i];
end;
end;
if ln=0 then write('Khong co so nguyen to')
else writeln(ln);
readln;
end.