#include <iostream>
#include <map>
#include <vector>
#define int long long
using namespace std;

const int N = 2e5+5;

int n,m,a[N];


void solve() {
    cin >> n >> m;

    int sum = 0;
    for(int i=1;i<=n;i++) cin >> a[i],sum+=a[i];
    int pre = 0;
    int tot = 0;
    int flag = 0;
    for(int i=1;i<=m;i++) {
        int x,y;
        cin >> x >> y;
        if(flag == 1) continue;
        x = x - pre;
        // cout << x << endl;
        if(sum >= x) sum -= x;
        else {
            cout << pre + sum << endl;
            for(;i<m;i++) cin >> x >> y;
            return;
            flag = 1;
        }
        tot += x;
        int dis = min(tot,a[y]);
        // cout<<dis<<' '<<sum<<endl;
        tot -= dis;
        sum += dis;
        // cout << sum << endl;
        pre = pre + x;
    }
    cout << pre + sum << endl;
}


signed main() {
    int t;
    cin >> t;
    // t = 1;
    while(t--) solve();
    return 0;
}