Problem:
Score: 300 points

Problem Statement

Find the minimum prime number greater than or equal to X.

Notes

A prime number is an integer greater than 1 that cannot be evenly divided by any positive integer except 1 and itself.

For example, 2, 3, and 5 are prime numbers, while 4 and 6 are not.

Constraints

2 \le X \le 10^5

All values in input are integers.

Input

Input is given from Standard Input in the following format:

X

Output

Print the minimum prime number greater than or equal to X.

Sample Input 1

20

Sample Output 1

23

The minimum prime number greater than or equal to 20 is 23.

Sample Input 2

2

Sample Output 2

2

X itself can be a prime number.

Sample Input 3

99992

Sample Output 3

100003

Solution in Pascal (FPC 3.0.4) (judge verdict: Runtime Error)

program main;

function checkprime (var y:integer): Boolean;
var a,counter : integer;
begin
counter:=0;
checkprime:=false;
for a:=1 to y do 
if (y mod counter=0) then counter:=counter+1;
if counter=2 then checkprime:=true;
if counter<>2 then checkprime:=false;
end;


var x : integer;
begin
readln (x);

repeat
if checkprime(x)=false then x:=x+1;
until checkprime(x)=true;

writeln (x);
end.