var n,x,k:longint;
    i,j:longint;
    a:array[1..10000]of char;
    f:text;
begin
assign(f,'ciur.in'); reset(f);
read(f,x);  close(f);
               j:=0;
for i:=1 to x-1 do

a[i]:='1';
  k:=2;


repeat
for j:=2 to x div k do

if (j*k<>0) and (j*k mod k=0) then a[j*k]:='0';
n:=n+1;
k:=k+1;
while a[k]='0' do k:=k+1;
until k=x;
n:=0;
assign(f,'ciur.out');rewrite(f);
write(f,k);
close(f);
end.