#include <bits/stdc++.h>
using namespace std;
const long long N = 3e5 + 20, M = 998244353;
#define eps 1e-12
#define int long long
// #define int __int128
#define ll long long
#define all(x) x.begin(), x.end()
#define endl '\n'
#define ls (p << 1)
#define rs ((p << 1) | 1)
#define f1 first
#define pb push_back
#define f2 second
#define IOS ios::sync_with_stdio(0), cin.tie(0), cout.tie(0), cout << fixed << setprecision(2);
int t, n, m, a[N], x[N], tr[N];
int b[N], x2[N], x3[N];
signed main()
{
	IOS;
	cin >> t;
	while (t--)
	{
		cin >> n >> m;
		deque<int> q;
		for (int i = 1; i <= n; i++)
			cin >> a[i], q.push_back(i), b[i] = a[i];
		for (int i = 1; i <= m; i++)
			cin >> x[i] >> tr[i], x2[i] = x[i] - x[i - 1], x3[i] = x[i];
		for (int i = 1; i <= m; i++)
			x[i] = x2[i];
		int ans = 0, j = 1;
		for (int i = 1; i <= m; i++)
		{
			j=max(j,i);
			while (1)
			{
				if (j > m)
				{
					while (q.size() && !b[q.back()])
						q.pop_back();
					if (!q.size())
					{
						ans = x3[i] - x[i];
						goto u;
					}
					int p = q.back();
					q.pop_back();
					if (b[p] >= x[i])
					{
						b[p] -= x[i];
						q.push_back(p);
						break;
					}
					else
					{
						x[i] -= b[p];
					}
				}
				int p = tr[j];
				if (b[p] >= x[i])
				{
					b[p]-=x[i];
					break;
				}
				else
				{
					x[i] -= b[p];
					b[p] = 0;
					j++;
				}
			}
			b[tr[i]] = a[tr[i]];
			q.push_back(tr[i]);
			if (i == m)
			{
				ans = x3[m];
				while (q.size())
					ans += b[q.front()],b[q.front()]=0, q.pop_front();
				goto u;
			}
		}
	u:;
		cout << ans << endl;
	}
	return false;
}