N, H = map(int, input().split())
weapon = [list(map(int, input().split())) for _ in range(N)]

count = 0

max_atack = -1
for i in range(N):
    max_atack = max(max_atack, weapon[i][0]) 


flag = True
for i in range(N):
    if weapon[i][1] >= max_atack:
        count += 1
        H -= weapon[i][1]
        
        if H <= 0:
            flag = False
            break

if flag:
    if H % max_atack == 0:
        count += H // max_atack
    else:
        count += H // max_atack + 1


print(count)