#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define int long long
const ll N=2e5+10;
ll n;
struct node{
	ll v,w;
}a[N],s[N];
bool cmp(node&a,node&b){
	if(a.v==b.v)return a.w<b.w;
	return a.v<b.v;
}
bool check(ll mid){
	for(int i=1;i<=n;i++){
		s[i]=a[i];
	}
	sort(s+1,s+n+1,[mid](node a,node b){
		if(max(a.v,mid)+a.w==max(b.v,mid)+b.w) return a.v<b.v;
		else return max(a.v,mid)+a.w<max(b.v,mid)+b.w;
		
	});
	int sum=0;
	for(int i=n;i>=1;i--){
		if(s[i].v<mid){
			sum--;
			if(sum<0) return 0;
		}
		else sum++;
	}
	return 1;
}
void solve(){
	cin>>n;
	for(ll i=1;i<=n;++i){
		cin>>a[i].v>>a[i].w;
	}
	sort(a+1,a+1+n,cmp);
	ll l=0,r=1e9+7;
	while(l<=r){
		ll mid=l+r>>1;
		if(check(mid))l=mid+1;
		else r=mid-1;
	}
	cout<<l-1<<endl;





}
signed main(void){
	ios::sync_with_stdio(0);
	cin.tie(0);cout.tie(0);
	ll Time=1;
	cin>>Time;
	while(Time--)solve();
	return 0;
}