import math
from operator import itemgetter

count = 0

N, H = list(map(int, input().split()))
ab = []

for i in range(N):
    ab.append(list(map(int, input().split())))

ab = sorted(ab, key=itemgetter(0,1), reverse=True)
max_a = ab[0][0]
for a_b in ab:
    if max_a <= a_b[1]:
        H -= a_b[1]
        count += 1

count += math.ceil(H / max_a)

print(count)