import math
N,H=[int(x) for x in input().split()]
a=[]
b=[]
for i in range(N):
    A,B=[int(x) for x in input().split()]
    a.append(A)
    b.append(B)
am = max(a)
b.sort(reverse=True)

count = 0
for i in b:
    if i < am:
        count += math.ceil(H/am)
        H = 0
    else:
        H -= i
        count += 1
if H > 0:
    count += math.ceil(H/am)
print(count)        
