content: import java.io.*;
  import java.math.*;
  import java.security.*;
  import java.text.*;
  import java.util.*;
  import java.util.concurrent.*;
  import java.util.regex.*;
  
  public class Solution {
  
      // Complete the arrayManipulation function below.
      static long arrayManipulation(int n, int[][] queries) {
      long[] computation = new long[n];
  
      for (int i = 0; i < queries.length; i++) {
        int a = queries[i][0] - 1;
        int b = queries[i][1] - 1;
        int k = queries[i][2];
  
        computation[a] += k;
        if (b + 1 < n ) {
          computation[b + 1] -= k;
        }
      }
  
      long max = 0; long sum = 0;
      for (int i = 0; i < n; i++) {
        sum += computation[i];
        max = Math.max(max, sum);
      }
  
      return max;
    }
  
      private static final Scanner scanner = new Scanner(System.in);
  
      public static void main(String[] args) throws IOException {
          BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter(System.getenv("OUTPUT_PATH")));
  
          String[] nm = scanner.nextLine().split(" ");
  
          int n = Integer.parseInt(nm[0]);
  
          int m = Integer.parseInt(nm[1]);
  
          int[][] queries = new int[m][3];
  
          for (int i = 0; i < m; i++) {
              String[] queriesRowItems = scanner.nextLine().split(" ");
              scanner.skip("(\r\n|[\n\r\u2028\u2029\u0085])?");
  
              for (int j = 0; j < 3; j++) {
                  int queriesItem = Integer.parseInt(queriesRowItems[j]);
                  queries[i][j] = queriesItem;
              }
          }
  
          long result = arrayManipulation(n, queries);
  
          bufferedWriter.write(String.valueOf(result));
          bufferedWriter.newLine();
  
          bufferedWriter.close();
  
          scanner.close();
      }
  }
  