include <bits/stdc++.h>

using namespace std; long long a[100007];

int main() {

long long n, m, x, y, ans = 0, num = 0;
cin >> n >> m;
if (m == 0) {
	cout << 0;
	return 0;
}
for (int i = 0; i < n; i++) {
	cin >> x >> y;
	a[i] = x - y;
}
sort(a, a + n);
for (int i = n - 1; i >= 0; i--) {
	ans += a[i];
	num += 1;
	if (ans >= m) {
		cout << num;
		return 0;
	}
}
cout << n;
return 0;

}