from math import ceil
N,H = map(int,input().split())
ab = [list(map(int,input().split())) for _ in range(N)]

amax = 0
for i in range(N):
    amax = max(amax,ab[i][0])

B = []
for i in range(N):
    if ab[i][1]>amax:
        B.append(ab[i][1])

ans = 0
for b in B:
    H -= b
    ans += 1
    if H <= 0:
        break

if H > 0:
    ans += ceil(H/amax)

print(ans)