#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;

int main()
{
       long int j,i,N,M,a,b,k,max=0;
       cin>>N>>M;
       long int *ar = new long int[N]();
       for(i=0;i<M;i++)
       {
              cin>>a>>b>>k;
              ar[a-1] = ar[a-1] + k;
              if(b<N)
              {
                     ar[b] = ar[b] - k;
              }
       }
       k = 0;
       for(i=0;i<N;i++)
       {
              k = k + ar[i];
              if(k>max)
              {
                     max = k;
              }
       }
       cout<<max<<endl;
       return 0;
}

• Problem Description
  You are given a list of size N, initialized with zeroes. You have to perform M operations on the list and output the maximum of final values of all the N elements in the list. For every operation, you are given three integers a,b and k and you have to add value k to all the elements ranging from index a to b (both inclusive).
  
  Input Format
  
  First line will contain two integers N and M separated by a single space. Next M lines will contain three integers a,b and k separated by a single space.
  
  Numbers in list are numbered from I to N.
  
  Constraints
  3<=N<=10^7 
  1<=M<=2 * 10 ^5 
  1<=a<=b<=N 
  0<=k<=10^9
  
  Output Format
  
  A single line containing maximum value in the updated list.
• Test Case 1
  Input (stdin)5 3
  1 2 100
  2 5 100
  3 4 100
  Expected Output200
• Test Case 2
  Input (stdin)4 2
  1 2 100
  3 4 100
  Expected Output100