include <bits/stdc++.h>

using namespace std; int main() {

long long i, j = 0, y, h, m, n, r, R[10000], k = 0;
cin >> n >> m;
if (m == 0) {
	cout << 0;
	return 0;
}
for (int i = 0; i < n; i++) {
	cin >> y >> h;
	r = y - h;
	R[i] = r;
}
sort(R, R + n, greater<long long>());

for (int i = 0; i < n; i++) {
	k++;
	j = R[i] + j;
	if (j >= m) {
		cout << k;
		return 0;
	}
}
long long  l;
l = j;
if (l < m) {
	cout << k;
	return 0;
}
return 0;

}

//sort(a,a+n,greater())