#include <cstdio>
#include <iostream>
#include <cstring>
#include <queue>
#include <cmath>
#include <set>
#include <algorithm>
#include <map>
#include <vector>
#define mod 1000000007
using namespace std;
typedef long long ll;

const int N = 106;
const double inf = 0x3f3f3f3f;
const double eps = 1e-6;


int main()
{
    int t, n, x, y, mx, my;
    scanf("%d", &t);
    while(t--){
        scanf("%d", &n);
        mx = my = 0;
        while(n--){
            scanf("%d%d", &x, &y);
            if(mx < x)
                mx = x;
            if(my < y)
                my = y;
        }
        printf("%d\n", mx+my);
    }
    return 0;
}