# Starting with a 1-indexed array of zeros and a list of operations, for each operation add a value to each of the array element between two given indices, inclusive. Once all operations have been performed, return the maximum value in your array.

# For example, the length of your array of zeros . Your list of queries is as follows:

#     a b k
#     1 5 3
#     4 8 7
#     6 9 1
# Add the values of  between the indices  and  inclusive:

# index->	 1 2 3  4  5 6 7 8 9 10
# 	[0,0,0, 0, 0,0,0,0,0, 0]
# 	[3,3,3, 3, 3,0,0,0,0, 0]
# 	[3,3,3,10,10,7,7,7,0, 0]
# 	[3,3,3,10,10,8,8,8,1, 0]
# The largest value is  after all operations are performed.

# Function Description

# Complete the function arrayManipulation in the editor below. It must return an integer, the maximum value in the resulting array.

# arrayManipulation has the following parameters:

# n - the number of elements in your array
# queries - a two dimensional array of queries where each queries[i] contains three integers, a, b, and k.
# Input Format

# The first line contains two space-separated integers  and , the size of the array and the number of operations.
# Each of the next  lines contains three space-separated integers ,  and , the left index, right index and summand.

# Constraints

# Output Format

# Return the integer maximum value in the finished array.

# Sample Input

# 5 3
# 1 2 100
# 2 5 100
# 3 4 100
# Sample Output

# 200
# Explanation

# After the first update list will be 100 100 0 0 0.
# After the second update list will be 100 200 100 100 100.
# After the third update list will be 100 200 200 200 100.
# The required answer will be 200.

#!/bin/python3

import math
import os
import random
import re
import sys

# Complete the arrayManipulation function below.
def arrayManipulation(n, queries):
    maxVal = 0
    current_int_value  = 0
    arr = [0] * n

    for query in queries:
        (a,b,k) = query
        arr[a-1] += k
        if b < len(arr):
            arr[b] -= k

    for i in range(n):
        current_int_value  += arr[i]
        maxVal = max(maxVal, current_int_value)

    return maxVal


if __name__ == '__main__':
    fptr = open(os.environ['OUTPUT_PATH'], 'w')

    nm = input().split()

    n = int(nm[0])

    m = int(nm[1])

    queries = []

    for _ in range(m):
        queries.append(list(map(int, input().rstrip().split())))

    result = arrayManipulation(n, queries)

    fptr.write(str(result) + '\n')

    fptr.close()
