source_code: import java.io.BufferedReader;
  import java.io.IOException;
  import java.io.InputStreamReader;
  import java.util.StringTokenizer;
  
  public class Main {
      public static void main(String[] args) throws IOException {
          BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
          StringTokenizer tokenizer = new StringTokenizer(reader.readLine());
          int n = Integer.parseInt(tokenizer.nextToken());
          int k = Integer.parseInt(tokenizer.nextToken());
          System.out.println((int)(n-(-3.0+Math.sqrt(9.0+8.0*(n+k)))/2.0));
      }
  }