#include <iostream>
#include <vector>

using namespace std;

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

    vector<int> cap(n);

    for (i = 0; i < n; i++)
    {
        cin >> cap[i];
    }

    vector<int> bins(n);

    pair<int, int> current;

    for (i = 0; i < k; i++)
    {
        cin >> current.first >> current.second;

        if (bins[current.first] + current.second > cap[current.first])
        {
            out += cap[current.first] - bins[current.first];
            bins[current.first] = current.second;
        }
        else
        {
            bins[current.first] += current.second;
        }
    }

    for (i = 0; i < n; i++)
    {
        if (bins[i])
        {
            out += cap[i] - bins[i];
        }
    }

    cout << out;
}
//5 7
//66 73 68 79 78
//2 50
//3 69
//0 1
//2 20
//4 12
//1 44
//3 11