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;
}
