var n,i,j:longint;
begin
  readln(n);
  if (n<=2)then begin writeln('0') ; halt; end;
  j:=trunc(sqrt(n));
  for i:=3 to j do
    begin
      if (n mod i=0) then break;
    end;
  writeln(i-1);
end.


Can anybody tell me why?
It seems rigth^Why ? It drives me crazy^

Edited by author 15.06.2008 14:10

Edited by author 15.06.2008 14:10

I think your j should be n div 2,and I promise it's not TLE.And you can define 'ans' to store the answer and let it equal n.That's all.

zj_zcy, what if n = 3 ?
Your program wrote 0, but right answer 2

The trouble is if n is big prime.
Try this:
99999989
The answer is:
99999988.

Think how to modify algorithm to catch big primes in factorization. Here it isn't necessary, but it will be useful.

Your code will possibly fail for integers like 2*n,also for test cases where n is a prime number