#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;
int main() {
	ios_base::sync_with_stdio(false);
	cin.tie(NULL); cout.tie(NULL);
	int N; 
	cin >> N;
	//<도착시간, 검문시간>
	vector<pair<int, int>> time;
	for (int i = 0; i < N; ++i) {
		int t1, t2;
		cin >> t1 >> t2;
		time.push_back({ t1, t2 });
	}
	//도착시간 기준 오름차순 정렬
	sort(time.begin(), time.end());
	int endTime = 0;
	for (int i = 0; i < N; ++i) {
		endTime = max(endTime, time[i].first);
		endTime += time[i].second;
	}
	cout << endTime;
	return 0;
}
