#include<bits/stdc++.h>
using namespace std;
#include<atcoder/all>
using namespace atcoder;
using mint=modint1000000007;
using ll=long long;
using P=pair<ll,ll>;
#define rep(i,N) for(int i=0;i<N;++i)
constexpr ll inf=1LL<<60;
ll N;
P v[1001];
int main(){
  cin>>N;
  rep(i,N){
    cin>>v[i].second>>v[i].first;
    v[i].first+=v[i].second;
  }
  sort(v,v+N);
  vector<ll> dp(N+1,inf);
  dp[0]=0;
  rep(i,N){
    auto[s,w]=v[i];
    for(int j=N-1;j>=0;--j){
      if(dp[j]+w<=s)dp[j+1]=min(dp[j+1],dp[j]+w);
    }
  }
  ll ans=0;
  while(ans<=N&&dp[ans]<inf)++ans;
  cout<<ans-1<<endl;
}