#include <bits/stdc++.h>
using namespace std;
#define int long long
#define sz(a) (int)(a.size())

signed main()
{
    int T;
    cin>>T;
    while(T--){
        int n, m;
        cin >> n >> m;
        vector<int> bat(n);
        for ( int& a: bat ) cin >> a;
        int prev = 0;
        int oob = 0;
        int remain = 0;
        for ( int& a: bat ) remain += a;
        int x, t;
        bool done = false;
        while ( m-- ) {
            cin >> x >> t; t--;
            if ( done ) continue;
            remain -= x-prev;
            if ( remain < 0 ) {
                cout << x+remain << '\n';
                done = true;
                continue;
            }
            oob += x-prev;
            int charge = min(bat[t], oob);
            remain += charge;
            oob -= charge;
            prev = x;
        }
        if ( !done ) cout << prev+remain << '\n';
    }
    return 0;

}