N,H = map(int,input().split())
src = [tuple(map(int,input().split())) for i in range(N)]
maxa = 0
bs = []
for a,b in src:
    maxa = max(maxa, a)
    bs.append(b)
bs.sort()

ans = 0
while bs:
    b = bs.pop()
    if b <= maxa: break
    H -= b
    ans += 1
    if H <= 0:
        print(ans)
        exit()

ans += -(-H//maxa)
print(ans)