source_code: import java.util.*;
  public class algo_1802
  {
      public static void main(String args[])
      {
          Scanner ex=new Scanner(System.in);
          int n=ex.nextInt();
          int k=ex.nextInt();
          int x=(int)((Math.sqrt(9.0+8.0*((double)n+(double)k))-3.0)/2.0);
          System.out.println(n-x);
      }
  }