Problem:
Score : 200 points

Problem Statement

Find the largest square number not exceeding N. Here, a square number is an integer that can be represented as the square of an integer.

Constraints

1 \leq N \leq 10^9

N is an integer.

Input

Input is given from Standard Input in the following format:

N

Output

Print the largest square number not exceeding N.

Sample Input 1

10

Sample Output 1

9

10 is not square, but 9 = 3 × 3 is. Thus, we print 9.

Sample Input 2

81

Sample Output 2

81

Sample Input 3

271828182

Sample Output 3

271821169

Solution in Pascal (FPC 2.6.2) (judge verdict: Accepted)

program Project1;
         
{$APPTYPE CONSOLE}
     
uses
  SysUtils,math;
var
  g,l,r,a,h,w,i,j,count,x,y,sw,m,n,b,c,soeji,sum,max,k,t:Integer;
  //l:array of Integer;
  s,s123,s1,s2,s3:string;
  tf:Boolean;
  //nyu:TStringList;
begin
  try
    { TODO -oUser -cConsole Main : ここにコードを記述してください }
    Readln(n);

    for i := n downto 1 do
      if power(trunc(sqrt(i)),2)=i then begin
        Writeln(i);
        break;
      end;
    Readln;
  except
    on E: Exception do
      Writeln(E.ClassName, ': ', E.Message);
  end;
end.