#include <bits/stdc++.h>
using namespace std;
#define int long long
typedef long long ll;

int n,m;
int a[2000000];
int b[2000000];
int x[2000000];
int t[2000000];

void solve()
{
    cin >> n >> m;
    int sum = 0;
    for (int i = 1;i<n+1;i++){
        cin >> a[i];
        sum += a[i];
        b[i] = a[i];
    }
    for (int i = 1;i<m+1;i++){
        cin >> x[i] >> t[i];
    }
    int daikuan = 0;
    int pos = 0;
    for (int i = 1;i<=m;i++){
        // cout<<i<<" "<<sum<<" "<<daikuan<<endl;
        if (sum - daikuan < x[i] - pos){
            cout<<i<<endl;
            break;
        }
        if (daikuan > b[t[i]]){
            daikuan -= b[t[i]];
            sum -= b[t[i]];
            b[t[i]] = 0;
        }else{
            sum -= daikuan;
            b[t[i]] -= daikuan;
            daikuan = 0;
        }
        if (x[i]-pos<=b[t[i]]){
            sum += a[t[i]] - b[t[i]];
            b[t[i]] = a[t[i]];
            pos = x[i];
        }else{
            sum += a[t[i]] - b[t[i]];
            daikuan += x[i] - pos - b[t[i]];
            b[t[i]] = a[t[i]];
            pos = x[i];
        }
    }
    // cout<<sum<<" "<<daikuan<<endl;
    pos += sum - daikuan;
    cout<<pos<<endl;
    return;
}
signed main()
{
    // freopen("input.txt", "r", stdin);
    // freopen("output.txt", "w", stdout);
    ios::sync_with_stdio(0), cin.tie(nullptr), cout.tie(0);
    int t = 1;
    cin >> t;
    while (t--)
    {
        solve();
    }
    return 0;
}