#include<bits/stdc++.h>
using namespace std;
#define pii pair<int,int>
#define int long long
#define x first
#define y second
void miss() {
    int n,m;
    cin >> n >> m;
    vector<int>ai(n + 1);
    int zlm = 0;
    for(int i = 1; i <= n; i++) {
        cin >> ai[i];
        zlm += ai[i];
    }
    pii q[m + 1];
    for(int i = 1; i <= m; i++) {
        cin >> q[i].x >> q[i].y;
    }
    int len = 0;
    int qqq = 0;
    for(int i = 1; i <= m; i++) {
        len = q[i].x - q[i - 1].x;
        if(len + qqq > zlm) {
            cout << q[i - 1].x + (zlm - qqq) << endl;
            return;
        }else {
            if(len + qqq > ai[q[i].y]) {
                qqq = (len + qqq) - ai[q[i].y];
            }
            else {
                qqq = 0;
            }
        }
    }
    cout << q[m].x + (zlm - qqq) << endl;
}
signed main() {
	ios::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	int T = 1;
	cin >> T;
	while(T--) miss();
	//system("pause");
}