#include <iostream>
using namespace std;
int main ( ) {
	long long komp,saveI;
	cin >> komp;
	long long width[komp], height[komp],namh[komp],namw[komp],sum;
	for (long long i = 0; i < komp;i++){
		cin >> width[i];
		namw[i]=width[i];
		cin >> height[i];
		namh[i] = height[i];
		for (saveI = i - 1;saveI > 0; saveI--){
			if (namh[i] == namh[saveI]){
				namw[saveI]+= namw[i];
			}
		}
	}
	sum = namw[0];
	for (long long i = 0; i < komp;i++){
		if (sum < namw[i]){
			sum = namw[i];
		}
	}
	cout << sum;
	return 0;
}
