#include <bits/stdc++.h>
#include<tuple>
#pragma GCC optimize("Ofast")

using namespace std;
typedef long double ld;
typedef long long int ll;
typedef unsigned long long int ull;
typedef vector<int> vi;
typedef vector<char> vc;
typedef vector<bool> vb;
typedef vector<double> vd;
typedef vector<string> vs;
typedef vector<ll> vll;
typedef vector<pair<int, int> > vpii;
typedef vector<vector<int> > vvi;
typedef vector<vector<char> > vvc;
typedef vector<vector<string> > vvs;
typedef vector<vector<ll> > vvll;
typedef vector<vector<bool> > vvb;

#define rep(i, n) for (int i = 0; i < (n); ++i)
#define rrep(i, n) for (int i = 1; i <= (n); ++i)
#define irep(it, stl) for (auto it = stl.begin(); it != stl.end(); it++)
#define drep(i, n) for (int i = (n)-1; i >= 0; --i)
#define mes(a) cout << (a) << endl
#define dmes(a, b) cout << (a) << " " << (b) << endl

#define CHOOSE(a) CHOOSE2 a
#define CHOOSE2(a0,a1,a2,a3,a4,x,...) x
#define debug_1(x1) cout<<#x1<<": "<<x1<<endl
#define debug_2(x1,x2) cout<<#x1<<": "<<x1<<", "#x2<<": "<<x2<<endl
#define debug_3(x1,x2,x3) cout<<#x1<<": "<<x1<<", "#x2<<": "<<x2<<", "#x3<<": "<<x3<<endl
#define debug_4(x1,x2,x3,x4) cout<<#x1<<": "<<x1<<", "#x2<<": "<<x2<<", "#x3<<": "<<x3<<", "#x4<<": "<<x4<<endl
#define debug_5(x1,x2,x3,x4,x5) cout<<#x1<<": "<<x1<<", "#x2<<": "<<x2<<", "#x3<<": "<<x3<<", "#x4<<": "<<x4<<", "#x5<<": "<<x5<<endl
#define debug(...) CHOOSE((__VA_ARGS__,debug_5,debug_4,debug_3,debug_2,debug_1,~))(__VA_ARGS__)

#define ynmes(a) (a) ? mes("Yes") : mes("No")
#define YNmes(a) (a) ? mes("YES") : mes("NO")
#define re0 return 0
#define mp(p, q) make_pair(p, q)
#define pb(n) push_back(n)
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define Sort(a) sort(a.begin(), a.end())
#define rSort(a) sort(a.rbegin(), a.rend())
#define Rev(a) reverse(a.begin(), a.end())
#define MATHPI acos(-1)
#define itn int;
int dx[8] = { 1, 0, -1, 0, 1, -1, -1, 1 };
int dy[8] = { 0, 1, 0, -1, 1, 1, -1, -1 };
template <class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template <class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }
struct io { io() { ios::sync_with_stdio(false); cin.tie(0); } };
const int INF = INT_MAX;
const ll LLINF = 1LL << 60;
const ll MOD = 1000000007;
const double EPS = 1e-9;

ll gcd(ll a, ll b) { return b ? gcd(b, a%b) : a; }
ll lcm(ll a, ll b) { return a / gcd(a, b) * b; }

ll modpow(ll x, ll y) {
    if(y == 1) {
        return x;
    }
    ll ans;
    if(y % 2 == 1) {
        ll r = modpow(x,(y-1)/2);
        ans = r * r % MOD;
        ans = ans * x % MOD;
    }
    else {
        ll r = modpow(x,y/2);
        ans = r * r % MOD;
    }
    return ans;
}

ll modncr(ll N, ll K) {
    ll res = 1;
    ll p=1;
    for (ll n = 0; n < K; ++n) {
      res = (res*(N - n))%MOD;
      p = (p*(n + 1))%MOD;
    }
    return (res*modpow(p,MOD-2))%MOD;
}


signed main() {
	ll n;
	cin >> n;
	vll a(n), b(n);
	vll s(n);
	map <ll, ll> mp;
	vector<tuple<ll, ll, ll> > tp(n);
	
	ll ss = 0;
	ll as = 0;
	rep(i, n) {
		cin >> a[i] >> b[i];
		s[i] = 2*a[i] + b[i];
		tp.pb(make_tuple(s[i], a[i], a[i]+b[i]));
		ss += a[i] + b[i];
		as += a[i];
	}
	
	
	rSort(tp);
	ll sum = 0; 
	ll pos = 1;
	while(sum <= as) {
		sum += get<2>(tp[pos-1]);
		as -= get<1>(tp[pos-1]);
		pos++;
	}
	
	
	
	mes(pos-1);
	
	
	
	
}


/**
 * Dont raise your voice, improve your argument.
 * --Desmond Tutu
 */
#include <bits/stdc++.h>
using namespace std;

const bool ready = [](){
    ios_base::sync_with_stdio(false); cin.tie(0);
    cout << fixed << setprecision(12);
    return true;
}();

using ld=long double;
const ld PI = acos((ld)-1);
using ll= long long;
#define int ll
#define all(v) (v).begin(), (v).end()
#define fori(n) for(int i=0; i<int(n); i++)

#define cini(i) int i; cin>>i;
#define cins(s) string s; cin>>s;
#define cind(d) ld d; cin>>d;
#define cinai(a,n) vi a(n); fori(n) { cin>>a[i]; }
#define cinas(s,n) vs s(n); fori(n) { cin>>s[i]; }
#define cinad(a,n) vd a(n); fori(n) { cin>>a[i]; }

using pii= pair<int, int>;
using pdd= pair<ld, ld>;
using vd= vector<ld>;
using vb= vector<bool>;
using vi= vector<int>;
using vvi= vector<vi>;
using vs= vector<string>;

#define endl "\n"

/* 
 * WA.
 * Some overflow?
 * Got the statement wrong?
 * -> villages are not sorted :/
 */
void solve() {
    cini(n);
    cini(k);

    vector<pii> ab(n);

    for(int i=0; i<n; i++)
        cin>>ab[i].first>>ab[i].second;

    sort(all(ab));

    int pos=0;
    for(int i=0; i<n; i++) {
        pos+=k;
        k=0;
        if(pos>=ab[i].first) {
            k+=ab[i].second;
        } else {
            break;
        }
    }
    pos+=k;
    cout<<pos<<endl;
}

signed main() {
    solve();
}