#include <bits/stdc++.h>
#define int int64_t

using std::cin;
using std::cout;
const char endl = '\n';

void solve() {
    int n, m;
    cin >> n >> m;
    std::vector<int> a(n + 1);
    int sum = 0;
    for (int i = 1; i <= n; ++i) cin >> a[i], sum += a[i];
    std::vector<int> x(m + 1), t(m + 1);
    for (int j = 1; j <= m; ++j) cin >> x[j] >> t[j];
    int now = 0;
    for (int j = 1; j <= m; ++j) {
        now -= x[j] - x[j - 1];
        if (now + sum < 0) {
            cout << (x[j] - (-now - sum)) << endl;
            return;
        }
        now += a[t[j]];
        if (now > 0) now = 0;
    }
    cout << x[m] + sum + now << endl;
}

int32_t main() {
#ifndef _DEBUG
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
#endif
    int tc = 1;
    std::cin >> tc;
    while (tc--) solve();
#ifdef _DEBUG
    std::cout << std::endl;
    std::cout << "Time used: " << clock() << "ms" << std::endl;
    system("pause");
    return 0;
#endif
}