/* -*- coding: utf-8 -*-
 *
 * 54.cc: No.54 Happy Hallowe'en - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

const int MAX_N = 10000;

/* typedef */

typedef pair<int,int> pii;
typedef set<int> si;

/* global variables */

pii vts[MAX_N];
si dp[MAX_N + 1];

/* subroutines */

bool cmp_vt(const pii &p0, const pii &p1) {
  return p0.first + p0.second < p1.first + p1.second;
}

/* main */

int main() {
  int n;
  cin >> n;

  for (int i = 0; i < n; i++) cin >> vts[i].first >> vts[i].second;
  sort(vts, vts + n, cmp_vt);

  dp[0].insert(0);

  for (int i = 0; i < n; i++) {
    int &vi = vts[i].first, &ti = vts[i].second;

    for (si::iterator sit = dp[i].begin(); sit != dp[i].end(); sit++) {
      dp[i + 1].insert(*sit);
      if (*sit < ti) dp[i + 1].insert(*sit + vi);
    }
  }

  printf("%d\n", *(dp[n].rbegin()));
  return 0;
}