#include<cstdio>

 #include<cstring>

 #include<algorithm>

 #include<queue>

 using namespace std;

 typedef long long ll;

 const int N = ;

 struct team{

     ll t, w, wa;

     team(ll t = , ll w = ):t(t),w(w) { wa = w - t + ; }

     bool operator < (const team &r)const{

         return r.wa < wa;

     }

 }a[N];

 bool cmp(team x, team y){

     return x.t > y.t;

 }

 priority_queue<team>q;

 int main(){

     int n, i, j;

     ll ans, a1;

     scanf("%d", &n);

     for(i = ; i < n; ++i)

         scanf("%lld%lld", &a[i].t, &a[i].w);

     sort(a+, a+n, cmp);

     for(i = ; i < n; ++i){

         if(a[i].t > a[].t)

             q.push(team(a[i].t, a[i].w));

         else break;

     }

     a1 = ans = i;//初始名次

     while(!q.empty()){

         team tt = q.top(); q.pop();

         a[].t -= tt.wa;

         if(a[].t < ) break;

         for(j = i; j < n; ++j){

             if(a[j].t > a[].t){

                 q.push(team(a[j].t , a[j].w));}

             else break;

         }

         a1 += j - i - ;

         i = j;

         ans = min(ans, a1);

     }

     printf("%lld\n", ans);

     return ;

 }