1 #include<cstdio>
 2 #include<queue>
 3 using namespace std;
 4 
 5 struct stone
 6 {
 7     int pos;
 8     int disc;
 9     bool operator < (const stone &temp)const
10     {
11         if(pos==temp.pos)
12         return disc>temp.disc;
13         return pos>temp.pos;
14     }
15 };
16 
17 int main()
18 {
19     int n,t;
20     scanf("%d",&t);
21     while(t--)
22     {
23         priority_queue<stone>q;
24         scanf("%d",&n);
25         bool flag=true;
26         while(n--)
27         {
28             stone node;
29             int temp1,temp2;
30             scanf("%d%d",&temp1,&temp2);
31             node.pos=temp1;
32             node.disc=temp2;
33             q.push(node);
34         }
35         int ans;
36         while(!q.empty())
37         {
38             stone node=q.top();
39             q.pop();
40             if(flag)
41             {
42                 node.pos+=node.disc;
43                 q.push(node);
44             }
45             ans=node.pos;
46             flag=!flag;
47         }
48         printf("%d\n",ans);
49     }
50     return 0;
51 }