import java.util.*;
// i hate myself
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        long k = in.nextLong();
        long[] a = new long[n];
        long[] b = new long[n];
        long max_a = -1L;
        for( int i = 0; i < n; i++ ) {
            a[i] = in.nextLong();
            b[i] = in.nextLong();
            max_a = Math.max(max_a, a[i]);
        }
        long ct = 0L;
        for( int i = 0; i < n; i++ ) {
            if(b[i] > max_a) {k -= b[i]; ct++;}
        }
        if( k>0 ) ct += Math.ceil((double)k/max_a);
        System.out.println(ct);
    }
}