L=list(map(int,input().split(" ")))
n=L.pop(0)
h=L.pop(0)
lst_a=[0 for i in range(n)]
lst_b=[0 for i in range(n)]
for i in range(n):
    L=list(map(int,input().split(" ")))
    lst_a[i]=L.pop(0)
    lst_b[i]=L.pop(0)


a_max=max(lst_a)
b_min=max(lst_b)
count=0

if sum(lst_b)<h:
    h_rest=h-sum(lst_b)
    if a_max>b_min:
        while h_rest<0:
            h_rest=h_rest-a_max
            count=count+1
    else:
        while a_max>lst_b[-1]:
            lst_b.pop(-1)
            h_rest=h_rest-a_max
            count=count+1
        while h_rest<0:
            h_rest=h_rest-a_max
            count=count+1
    print(count)
else:
    while h<0:
        h=h-lst_b.pop(-1)    
    print(count)
 