#include <bits/stdc++.h>

#define ll long long
#define pb push_back
#define f first
#define s second
#define sz(x) (int)(x).size()
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define ios ios_base::sync_with_stdio(false);cin.tie(NULL)
#define ld long double
#define li __int128

using namespace std;

mt19937 rng(time(NULL));

int main()
{
	ios;
	int t;
	cin >> t;
	while(t--){
		int n,m;
		cin >> n >> m;
		ll b=0;
		vector<int> a(n);
		for(int i=0;i<n;i++){
			cin >> a[i];
			b+=a[i];
		}
		ll potrosio=0;
		int p=0;
		bool done=0;
		pair<ll,int> nesme={0,-1};
		for(int i=0;i<m;i++){
			int x,t;
			cin >> x >> t;
			t--;
			if(done)continue;
			int d=x-p;
			if(potrosio+d>b){
				printf("%lld\n",p+b-potrosio);
				done=1;
			}
			potrosio+=d;
			if(nesme.s==t){
				ll smem=potrosio-nesme.s;
				ll ref;
				if(smem>a[t]){
					ref=a[t];
					nesme.f+=smem-a[t];
				}
				else{
					ref=smem;
				}
				potrosio-=ref;
			}
			else{
				ll tokens=a[t];
				if(tokens>=nesme.f){
					potrosio-=nesme.f;
					nesme={0,-1};
					tokens-=nesme.f;
				}
				if(potrosio>tokens){
					potrosio-=tokens;
					nesme={potrosio,t};
				}
				else{
					potrosio=0;
				}
			}
			p=x;
		}
		if(!done){
			printf("%lld\n",p+b-potrosio);
		}
	}
	return 0;
}