throw = []
blow = 0
cnt = 0
n,h = map(int, input().split())
for _ in range(n):
  a,b = map(int, input().split())
  blow = max(blow,a)
  throw.append(b)
throw.sort()
while h>0 and throw and throw[-1]>blow:
  h -= throw.pop()
  cnt += 1
if h > 0:
  cnt += h//blow + (h%blow>0)
print(cnt)