source_code: 
  
  
  import java.util.*;
  
  public class Temppp {
  
      public static void main(String[] args) {
          
          Scanner sc = new Scanner(System.in);
          long n = sc.nextLong();
          long k = sc.nextLong();
         
          long ans = (long) ((java.lang.Math.sqrt((9+(8*(n+k))))-3)/2);
          System.out.println(n-ans);
          
      }
      
  }
  