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

using namespace std;

int main(){
	int n,p;
	cin >> n >> p;
	vector<int>score(n);
	for ( int i = 0; i < n; i++){
		cin >> score[i];
	}
	vector<int>adjacency(score.size());
	adjacent_difference(score.begin(),score.end(),adjacency.begin());
	int x,y,z;
	while(p--){
		cin >> x >> y >> z;
		adjacency[x - 1] += z;
		adjacency[y] -= z;
	}
	vector<int>ans(adjacency.size());
	partial_sum(adjacency.begin(),adjacency.end(),ans.begin());
	sort(ans.begin(),ans.end());
	cout << ans[0] << endl;

	return 0;
}