#include<stdio.h>
#define MIN(a,b) a < b ? a : b

int main(){
	int n, p;
	int left, right, score;
	scanf("%d %d", &n, &p);
	int A[n + 1], B[n + 1];
	A[0] = 0;
	B[0] = 0;
	int min = 999999;
	int data = 0;
	for(int i = 1 ;i <= n;i ++){
		scanf("%d", &A[i]);
	}
	for(int i = 1;i <= n;i ++){
		B[i] = A[i] - A[i - 1];
	}
	for(int i = 0;i < p;i ++){
		scanf("%d %d %d", &left, &right, &score);
		B[right + 1] -= score;
		B[left] += score;
	}

	for(int i = 1;i <= n;i ++){
		data += B[i];
		min = MIN(data,min);
	}
	printf("%d", min);
	return 0;
}