#include <bits/stdc++.h>
#include <algorithm>

using namespace std;

int main() {
    int n, m;
    cin >> n >> m;
    vector<long long> v(n);
    for(int a0 = 0; a0 < m; a0++){
        int start, end, val;
        cin >> start >> end >> val;
        auto it_start = v.begin()+(start-1);
        auto it_end = v.begin()+(end);
        transform(it_start, it_end , it_start, [k](long long &x){return x+=k;});
    }
    cout << *max_element(v.begin(),v.end());
    return 0;
}

#include <algorithm>
#include <vector>
#include <iostream>

int main() {
    int n; int m;
    std::cin >> n >> m;
    using val_type = long long;
    std::vector<val_type> v(n);
    while(m--){
        val_type start, end, val;
        std::cin >> start >> end >> val;
        auto it_start = v.begin()+(start-1);
        auto it_end   = v.begin()+ end;
        *it_start     += val;
        *it_end       -= val;
    }
    val_type max{0};
    auto accumulate_max_val = [x=val_type(0),&max](val_type y) mutable {x+=y; if (x>max) max=x;};
    std::for_each(v.begin(),v.end(),accumulate_max_val);
    std::cout << max;
    return 0;
}