#include <iostream>

 #include <algorithm>

 #include <functional>

 using namespace std;

 typedef long long LL_INT;

 typedef struct _cows

 {

     LL_INT strength;

     LL_INT weight;

     bool operator<(const  _cows &x) const

     {

         return strength + weight > x.weight + x.strength;

     }

 }Cows;

 static Cows cows_set[];

 void Search(const int, LL_INT);

 bool judge(const LL_INT, const int,const LL_INT);

 int main(void)

 {

     int sum_cows;

     LL_INT sum_w;

     while (~scanf("%d", &sum_cows))

     {

         sum_w = ;

         for (int i = ; i < sum_cows; i++)

         {

             scanf("%lld%lld", &cows_set[i].weight, &cows_set[i].strength);

             sum_w += cows_set[i].weight;

         }

         sort(cows_set, cows_set + sum_cows);

         Search(sum_cows,sum_w);

     }

     return ;

 }

 void Search(const int sum_cows, LL_INT sum_w)

 {

     LL_INT ans = -;

     for (int i = ; i < sum_cows; i++)

     {

         sum_w -= cows_set[i].weight;

         ans = max(ans, sum_w - cows_set[i].strength);

     }

     cout << ans << endl;

 }