/* package whatever; // don't place package name! */
import java.util.*;
import java.lang.*;
import java.io.*;
/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
{
Scanner sc
= new Scanner
(System.
in);
int n
= Integer.
parseInt(sc.
nextLine()); int a = 0;
int b = 0;
for (int i = 1; i <= n; i++) {
if ( i > a) {
b++;
a = a + b;
}
}
}
}
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