#include <iostream>
#include <vector>

using namespace std;

int main()
{
    int n, k, capacity, type, amount, i, out = 0;
    cin >> n >> k;

    vector<pair<int, int>> trash(n, { 0,0 });
    for (i = 0; i < n; i++) {
        cin >> trash[i].second;
    }

    for (i = 0; i < k; i++) {
        cin >> type >> amount;
        if (trash[type].first + amount < trash[type].second) {
            trash[type].first += amount;
        }
        else if (trash[type].first + amount == trash[type].second) {
            trash[type].first = 0;
        }
        else {
            out += trash[type].second - trash[type].first;
            trash[type].first = amount;
        }
    }
    for (i = 0; i < n; i++) {
        if (trash[i].first > 0) {
            out += trash[i].second - trash[i].first;
        }
    }

    cout << out;
}