n, h = map(int, input().split())
sords = [list(map(int, input().split())) for _ in range(n)]
best = sorted(sords)[-1][0]
throw_damage = 0
cnt = 0
for i in sords:
    if i[1] > best:
        throw_damage += i[1]
        cnt += 1
print(cnt if throw_damage >= h else cnt + (h - throw_damage) // best + ((h - throw_damage)%best != 0))