import sys
input = sys.stdin.readline
n, h = map(int, input().split())
ab = []
for i in range(n):
  a, b = map(int, input().split())
  ab.append((-a, b, i))
  
ab.sort()
index = ab[0][2]

ab2 = ab[:]
ab2.sort(key = lambda x:x[1], reverse = True)

cnt = 0

for a, b ,i in ab2:
  if h <= 0:
    print(cnt)
    sys.exit()
  a = -a
  if i == index:
    print(1+cnt+ max(0, h - b + a - 1) // a)
    sys.exit()
  else:
    h -= b
    cnt += 1
