#include<bits/stdc++.h>

#define fi first
#define se second
#define sz(x) (int)(x).size()
#define pb push_back
#define rep(i, a, b) for (int i = a; i < (b); ++i)
#define all(x) begin(x), end(x)


using namespace std;


using pii = pair<int, int>;
using vi = vector<int>;
using ll = long long;



#ifdef DEBUG
auto&operator<<(auto&o,pair<auto,auto>p){return o<<"("<<p.first<<", "<<p.second<<")";}
auto operator<<(auto&o,auto x)->decltype(x.end(),o){o<<"{";int i=0;for(auto e:x)o<<","+!i++<<e;return o<<"}";}
#define debug(x...) cerr<<"["#x"]: ",[](auto...$){((cerr<<$<<"; "),...)<<endl;}(x)
#else
#define debug(...) {}
#endif

void solve(){

   int n;
   cin >> n;
   vector < int > s(n);
   vector < int > have(n);

   vector < pair < int , int > > events;
   for(int i = 0; i < n; ++i){
        int r;
        cin >> r >> s[i];
        events.push_back({max(0 , i - r) , i});
        events.push_back({min(n + 1, i + r + 1), i});
   }
   int ptr = 0;

   multiset<int> vals;

   ll answer = 0;

   sort(all(events));
   for(auto &i : events){
        while(ptr < sz(events) && events[ptr].fi <= i.fi){
            int ind = events[ptr].se;
            if(!have[ind]){
                debug("add ", ind);
                vals.insert(s[ind]);
                have[ind] = 1;
            }else{
                debug("rase " , ind);
                vals.erase(vals.find(s[ind]));
            }
            ++ptr;
        }
        if(sz(vals) >= 3){
            auto it = vals.end();
            ll cur_ans = *(--it) + *(--it) + *(--it);
            answer = max(answer , cur_ans);
        }

        debug("lol ", i.fi,  vals);
   }
   cout << answer << '\n';
}
int main(){
    cin.tie(0)->sync_with_stdio(false);
    cin.exceptions(cin.failbit);


    int t;
    cin >> t;
    while(t--){
        solve();
    }

    return 0;
}
/*
3
4
1 39
2 17
4 5
1 40
3
1 10
1 20
1 30
7
5 4
4 3
3 2
2 1
3 2
4 3
5 4
*/