import math
N, HP = map(int, input().split())
 
hit = 0
throw = []
for i in range(N):
    h, t = map(int, input().split())
    if h > hit:
        hit = h
    throw.append(t)
 
throw.sort()
 
 
ans = 0
for t in throw[::-1]:
    if t < hit:
        break
    else:
        ans += 1
        HP -= t
        if HP <= 0:
            break
if HP > 0:
  ans += math.ceil(HP // hit)
 
print(ans)