#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <set>
#include <map>
#include <climits>

using namespace std;

int main()
{
	int N, K;
	cin >> N >> K;
	
	vector<int> c;
	vector<int> t;
	long int cost = 0;
	for (int i = 0; i < N; i++)
	{
		int next;
		cin >> next;
		c.push_back(next);
		t.push_back(0);
	}

	for (int i = 0; i < K; i++)
	{
		int index, trash;
		cin >> index >> trash;
		long int newTrash = t[index] + trash;
		if (newTrash > c[index])
		{
			cost += c[index] - t[index];
			t[index] = trash;
		}
		else
		{
			t[index] += trash;
		}
	}

	for (int i = 0; i < N; i++)
	{
		cost += t[i] == 0 ? 0 : c[i] - t[i];
	}

	cout << cost;
}