#include <iostream>
#include <algorithm>
#include <cstring>

using namespace std;

#define x first
#define y second

typedef pair<int, int> PII;

const int N = 1e3 + 10;

int n, b;
PII p[N];
int a[N];

bool cmp(PII a, PII b)
{
    return a.x + a.y < b.x + b.y;
}

int main()
{
    cin >> n >> b;
    for(int i = 0; i < n; i ++ )
    {
        cin >> p[i].x >> p[i].y;
    }
    sort(p, p + n, cmp);

    int sum = 0;
    for(int i = 0; i < n; i ++ )
    {
        if(b >= p[i].x + p[i].y)
        {
            b = b - p[i].x - p[i].y;
            sum ++;
        } 
        else if(b >= p[i].x / 2 + p[i].y)
        {
            b = b - p[i].x - p[i].y;
            sum ++;
        }
        else
        {
            break;
        }
    }

    cout << sum << endl;

    return 0;
}