#input
n, h = map(int, input().split())
A = []
B = []
for i in range(n):
    a, b = map(int,input().split())
    A.append(a)
    B.append(b)
#manipulation
count = 0
for b in B:
    if b >= max(A):
        h -= b
        count += 1
count += h // max(A)
if h % max(A) != 0:
    count += 1
#output
print(count)