import java.util.Scanner ;

public class Main {

public static void main(String[] args) {

// Write your code here

int i = 1 , result =1 ;

Scanner s = new Scanner(System.in);

int N = s.nextInt();

while(result<=N) {

i++ ;

result = i*i ;

}

System.out.println( i- 1 );

}

}