#include<iostream>
#include<sstream>
#include<string>
#include<vector>
#include<list>
#include<set>
#include<map>
#include<stack>
#include<queue>
#include<algorithm>
#pragma warning(disable:4996)
using std::cin;
using std::cout;
using std::endl;
using std::stringstream;
using std::string;
using std::vector;
using std::list;
using std::pair;
using std::set;
using std::multiset;
using std::map;
using std::multimap;
using std::stack;
using std::queue;
using std::priority_queue;
class Turtle
{
public:
int weight, strength;
friend bool operator < (const Turtle &a, const Turtle &b)
{
return a.strength < b.strength;
}
Turtle()
{
weight = 0;
strength = 0;
}
Turtle(const int &w, const int &s)
{
weight = w;
strength = s;
}
};
int main()
{
//freopen("input.txt", "r", stdin);
//freopen("output.txt", "w", stdout);
vector<Turtle>turtle(1);
int weight, strength;
while (cin >> weight >> strength)
{
turtle.push_back({ weight,strength });
}
std::sort(turtle.begin()+1, turtle.end());
vector<vector<int>>dp(turtle.size(), (vector<int>)turtle.size());
for (size_t i = 0; i < turtle.size(); i++)
{
dp[i][0] = 0;
for (int j = 1; j < turtle.size(); ++j)
{
dp[i][j] = 2000000000;
}
}
for (size_t i = 1; i <turtle.size(); i++)
{
for (size_t j = 1; j <= i; j++)
{
dp[i][j] = dp[i - 1][j];
if (turtle[i].strength - turtle[i].weight >= dp[i - 1][j - 1] && dp[i - 1][j - 1] != 2000000000)
{
dp[i][j] = std::min(dp[i][j], dp[i - 1][j - 1] + turtle[i].weight);
}
}
}
for (size_t i = turtle.size()-1; i >= 1; i--)
{
if (dp[turtle.size() - 1][i] != 2000000000)
{
cout << i << endl;
break;
}
}
return 0;
}